mm/vmstat.c

   1 /*
   2  *  linux/mm/vmstat.c
   3  *
   4  *  Manages VM statistics
   5  *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
   6  *
   7  *  zoned VM statistics
   8  *  Copyright (C) 2006 Silicon Graphics, Inc.,
   9  *              Christoph Lameter <christoph@lameter.com>
  10  *  Copyright (C) 2008-2014 Christoph Lameter
  11  */
  12 #include <linux/fs.h>
  13 #include <linux/mm.h>
  14 #include <linux/err.h>
  15 #include <linux/module.h>
  16 #include <linux/slab.h>
  17 #include <linux/cpu.h>
  18 #include <linux/cpumask.h>
  19 #include <linux/vmstat.h>
  20 #include <linux/proc_fs.h>
  21 #include <linux/seq_file.h>
  22 #include <linux/debugfs.h>
  23 #include <linux/sched.h>
  24 #include <linux/math64.h>
  25 #include <linux/writeback.h>
  26 #include <linux/compaction.h>
  27 #include <linux/mm_inline.h>
  28 #include <linux/page_ext.h>
  29 #include <linux/page_owner.h>
  30
  31 #include "internal.h"
  32
  33 #define NUMA_STATS_THRESHOLD (U16_MAX - 2)
  34
  35 #ifdef CONFIG_NUMA
  36 int sysctl_vm_numa_stat = ENABLE_NUMA_STAT;
  37
  38 /* zero numa counters within a zone */
  39 static void zero_zone_numa_counters(struct zone *zone)
  40 {
  41         int item, cpu;
  42
  43         for (item = 0; item < NR_VM_NUMA_STAT_ITEMS; item++) {
  44                 atomic_long_set(&zone->vm_numa_stat[item], 0);
  45                 for_each_online_cpu(cpu)
  46                         per_cpu_ptr(zone->pageset, cpu)->vm_numa_stat_diff[item]
  47                                                 = 0;
  48         }
  49 }
  50
  51 /* zero numa counters of all the populated zones */
  52 static void zero_zones_numa_counters(void)
  53 {
  54         struct zone *zone;
  55
  56         for_each_populated_zone(zone)
  57                 zero_zone_numa_counters(zone);
  58 }
  59
  60 /* zero global numa counters */
  61 static void zero_global_numa_counters(void)
  62 {
  63         int item;
  64
  65         for (item = 0; item < NR_VM_NUMA_STAT_ITEMS; item++)
  66                 atomic_long_set(&vm_numa_stat[item], 0);
  67 }
  68
  69 static void invalid_numa_statistics(void)
  70 {
  71         zero_zones_numa_counters();
  72         zero_global_numa_counters();
  73 }
  74
  75 static DEFINE_MUTEX(vm_numa_stat_lock);
  76
  77 int sysctl_vm_numa_stat_handler(struct ctl_table *table, int write,
  78                 void __user *buffer, size_t *length, loff_t *ppos)
  79 {
  80         int ret, oldval;
  81
  82         mutex_lock(&vm_numa_stat_lock);
  83         if (write)
  84                 oldval = sysctl_vm_numa_stat;
  85         ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
  86         if (ret || !write)
  87                 goto out;
  88
  89         if (oldval == sysctl_vm_numa_stat)
  90                 goto out;
  91         else if (sysctl_vm_numa_stat == ENABLE_NUMA_STAT) {
  92                 static_branch_enable(&vm_numa_stat_key);
  93                 pr_info("enable numa statistics\n");
  94         } else {
  95                 static_branch_disable(&vm_numa_stat_key);
  96                 invalid_numa_statistics();
  97                 pr_info("disable numa statistics, and clear numa counters\n");
  98         }
  99
 100 out:
 101         mutex_unlock(&vm_numa_stat_lock);
 102         return ret;
 103 }
 104 #endif
 105
 106 #ifdef CONFIG_VM_EVENT_COUNTERS
 107 DEFINE_PER_CPU(struct vm_event_state, vm_event_states) = {{0}};
 108 EXPORT_PER_CPU_SYMBOL(vm_event_states);
 109
 110 static void sum_vm_events(unsigned long *ret)
 111 {
 112         int cpu;
 113         int i;
 114
 115         memset(ret, 0, NR_VM_EVENT_ITEMS * sizeof(unsigned long));
 116
 117         for_each_online_cpu(cpu) {
 118                 struct vm_event_state *this = &per_cpu(vm_event_states, cpu);
 119
 120                 for (i = 0; i < NR_VM_EVENT_ITEMS; i++)
 121                         ret[i] += this->event[i];
 122         }
 123 }
 124
 125 /*
 126  * Accumulate the vm event counters across all CPUs.
 127  * The result is unavoidably approximate - it can change
 128  * during and after execution of this function.
 129 */
 130 void all_vm_events(unsigned long *ret)
 131 {
 132         get_online_cpus();
 133         sum_vm_events(ret);
 134         put_online_cpus();
 135 }
 136 EXPORT_SYMBOL_GPL(all_vm_events);
 137
 138 /*
 139  * Fold the foreign cpu events into our own.
 140  *
 141  * This is adding to the events on one processor
 142  * but keeps the global counts constant.
 143  */
 144 void vm_events_fold_cpu(int cpu)
 145 {
 146         struct vm_event_state *fold_state = &per_cpu(vm_event_states, cpu);
 147         int i;
 148
 149         for (i = 0; i < NR_VM_EVENT_ITEMS; i++) {
 150                 count_vm_events(i, fold_state->event[i]);
 151                 fold_state->event[i] = 0;
 152         }
 153 }
 154
 155 #endif /* CONFIG_VM_EVENT_COUNTERS */
 156
 157 /*
 158  * Manage combined zone based / global counters
 159  *
 160  * vm_stat contains the global counters
 161  */
 162 atomic_long_t vm_zone_stat[NR_VM_ZONE_STAT_ITEMS] __cacheline_aligned_in_smp;
 163 atomic_long_t vm_numa_stat[NR_VM_NUMA_STAT_ITEMS] __cacheline_aligned_in_smp;
 164 atomic_long_t vm_node_stat[NR_VM_NODE_STAT_ITEMS] __cacheline_aligned_in_smp;
 165 EXPORT_SYMBOL(vm_zone_stat);
 166 EXPORT_SYMBOL(vm_numa_stat);
 167 EXPORT_SYMBOL(vm_node_stat);
 168
 169 #ifdef CONFIG_SMP
 170
 171 int calculate_pressure_threshold(struct zone *zone)
 172 {
 173         int threshold;
 174         int watermark_distance;
 175
 176         /*
 177          * As vmstats are not up to date, there is drift between the estimated
 178          * and real values. For high thresholds and a high number of CPUs, it
 179          * is possible for the min watermark to be breached while the estimated
 180          * value looks fine. The pressure threshold is a reduced value such
 181          * that even the maximum amount of drift will not accidentally breach
 182          * the min watermark
 183          */
 184         watermark_distance = low_wmark_pages(zone) - min_wmark_pages(zone);
 185         threshold = max(1, (int)(watermark_distance / num_online_cpus()));
 186
 187         /*
 188          * Maximum threshold is 125
 189          */
 190         threshold = min(125, threshold);
 191
 192         return threshold;
 193 }
 194
 195 int calculate_normal_threshold(struct zone *zone)
 196 {
 197         int threshold;
 198         int mem;        /* memory in 128 MB units */
 199
 200         /*
 201          * The threshold scales with the number of processors and the amount
 202          * of memory per zone. More memory means that we can defer updates for
 203          * longer, more processors could lead to more contention.
 204          * fls() is used to have a cheap way of logarithmic scaling.
 205          *
 206          * Some sample thresholds:
 207          *
 208          * Threshold    Processors      (fls)   Zonesize        fls(mem+1)
 209          * ------------------------------------------------------------------
 210          * 8            1               1       0.9-1 GB        4
 211          * 16           2               2       0.9-1 GB        4
 212          * 20           2               2       1-2 GB          5
 213          * 24           2               2       2-4 GB          6
 214          * 28           2               2       4-8 GB          7
 215          * 32           2               2       8-16 GB         8
 216          * 4            2               2       <128M           1
 217          * 30           4               3       2-4 GB          5
 218          * 48           4               3       8-16 GB         8
 219          * 32           8               4       1-2 GB          4
 220          * 32           8               4       0.9-1GB         4
 221          * 10           16              5       <128M           1
 222          * 40           16              5       900M            4
 223          * 70           64              7       2-4 GB          5
 224          * 84           64              7       4-8 GB          6
 225          * 108          512             9       4-8 GB          6
 226          * 125          1024            10      8-16 GB         8
 227          * 125          1024            10      16-32 GB        9
 228          */
 229
 230         mem = zone->managed_pages >> (27 - PAGE_SHIFT);
 231
 232         threshold = 2 * fls(num_online_cpus()) * (1 + fls(mem));
 233
 234         /*
 235          * Maximum threshold is 125
 236          */
 237         threshold = min(125, threshold);
 238
 239         return threshold;
 240 }
 241
 242 /*
 243  * Refresh the thresholds for each zone.
 244  */
 245 void refresh_zone_stat_thresholds(void)
 246 {
 247         struct pglist_data *pgdat;
 248         struct zone *zone;
 249         int cpu;
 250         int threshold;
 251
 252         /* Zero current pgdat thresholds */
 253         for_each_online_pgdat(pgdat) {
 254                 for_each_online_cpu(cpu) {
 255                         per_cpu_ptr(pgdat->per_cpu_nodestats, cpu)->stat_threshold = 0;
 256                 }
 257         }
 258
 259         for_each_populated_zone(zone) {
 260                 struct pglist_data *pgdat = zone->zone_pgdat;
 261                 unsigned long max_drift, tolerate_drift;
 262
 263                 threshold = calculate_normal_threshold(zone);
 264
 265                 for_each_online_cpu(cpu) {
 266                         int pgdat_threshold;
 267
 268                         per_cpu_ptr(zone->pageset, cpu)->stat_threshold
 269                                                         = threshold;
 270
 271                         /* Base nodestat threshold on the largest populated zone. */
 272                         pgdat_threshold = per_cpu_ptr(pgdat->per_cpu_nodestats, cpu)->stat_threshold;
 273                         per_cpu_ptr(pgdat->per_cpu_nodestats, cpu)->stat_threshold
 274                                 = max(threshold, pgdat_threshold);
 275                 }
 276
 277                 /*
 278                  * Only set percpu_drift_mark if there is a danger that
 279                  * NR_FREE_PAGES reports the low watermark is ok when in fact
 280                  * the min watermark could be breached by an allocation
 281                  */
 282                 tolerate_drift = low_wmark_pages(zone) - min_wmark_pages(zone);
 283                 max_drift = num_online_cpus() * threshold;
 284                 if (max_drift > tolerate_drift)
 285                         zone->percpu_drift_mark = high_wmark_pages(zone) +
 286                                         max_drift;
 287         }
 288 }
 289
 290 void set_pgdat_percpu_threshold(pg_data_t *pgdat,
 291                                 int (*calculate_pressure)(struct zone *))
 292 {
 293         struct zone *zone;
 294         int cpu;
 295         int threshold;
 296         int i;
 297
 298         for (i = 0; i < pgdat->nr_zones; i++) {
 299                 zone = &pgdat->node_zones[i];
 300                 if (!zone->percpu_drift_mark)
 301                         continue;
 302
 303                 threshold = (*calculate_pressure)(zone);
 304                 for_each_online_cpu(cpu)
 305                         per_cpu_ptr(zone->pageset, cpu)->stat_threshold
 306                                                         = threshold;
 307         }
 308 }
 309
 310 /*
 311  * For use when we know that interrupts are disabled,
 312  * or when we know that preemption is disabled and that
 313  * particular counter cannot be updated from interrupt context.
 314  */
 315 void __mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
 316                            long delta)
 317 {
 318         struct per_cpu_pageset __percpu *pcp = zone->pageset;
 319         s8 __percpu *p = pcp->vm_stat_diff + item;
 320         long x;
 321         long t;
 322
 323         x = delta + __this_cpu_read(*p);
 324
 325         t = __this_cpu_read(pcp->stat_threshold);
 326
 327         if (unlikely(x > t || x < -t)) {
 328                 zone_page_state_add(x, zone, item);
 329                 x = 0;
 330         }
 331         __this_cpu_write(*p, x);
 332 }
 333 EXPORT_SYMBOL(__mod_zone_page_state);
 334
 335 void __mod_node_page_state(struct pglist_data *pgdat, enum node_stat_item item,
 336                                 long delta)
 337 {
 338         struct per_cpu_nodestat __percpu *pcp = pgdat->per_cpu_nodestats;
 339         s8 __percpu *p = pcp->vm_node_stat_diff + item;
 340         long x;
 341         long t;
 342
 343         x = delta + __this_cpu_read(*p);
 344
 345         t = __this_cpu_read(pcp->stat_threshold);
 346
 347         if (unlikely(x > t || x < -t)) {
 348                 node_page_state_add(x, pgdat, item);
 349                 x = 0;
 350         }
 351         __this_cpu_write(*p, x);
 352 }
 353 EXPORT_SYMBOL(__mod_node_page_state);
 354
 355 /*
 356  * Optimized increment and decrement functions.
 357  *
 358  * These are only for a single page and therefore can take a struct page *
 359  * argument instead of struct zone *. This allows the inclusion of the code
 360  * generated for page_zone(page) into the optimized functions.
 361  *
 362  * No overflow check is necessary and therefore the differential can be
 363  * incremented or decremented in place which may allow the compilers to
 364  * generate better code.
 365  * The increment or decrement is known and therefore one boundary check can
 366  * be omitted.
 367  *
 368  * NOTE: These functions are very performance sensitive. Change only
 369  * with care.
 370  *
 371  * Some processors have inc/dec instructions that are atomic vs an interrupt.
 372  * However, the code must first determine the differential location in a zone
 373  * based on the processor number and then inc/dec the counter. There is no
 374  * guarantee without disabling preemption that the processor will not change
 375  * in between and therefore the atomicity vs. interrupt cannot be exploited
 376  * in a useful way here.
 377  */
 378 void __inc_zone_state(struct zone *zone, enum zone_stat_item item)
 379 {
 380         struct per_cpu_pageset __percpu *pcp = zone->pageset;
 381         s8 __percpu *p = pcp->vm_stat_diff + item;
 382         s8 v, t;
 383
 384         v = __this_cpu_inc_return(*p);
 385         t = __this_cpu_read(pcp->stat_threshold);
 386         if (unlikely(v > t)) {
 387                 s8 overstep = t >> 1;
 388
 389                 zone_page_state_add(v + overstep, zone, item);
 390                 __this_cpu_write(*p, -overstep);
 391         }
 392 }
 393
 394 void __inc_node_state(struct pglist_data *pgdat, enum node_stat_item item)
 395 {
 396         struct per_cpu_nodestat __percpu *pcp = pgdat->per_cpu_nodestats;
 397         s8 __percpu *p = pcp->vm_node_stat_diff + item;
 398         s8 v, t;
 399
 400         v = __this_cpu_inc_return(*p);
 401         t = __this_cpu_read(pcp->stat_threshold);
 402         if (unlikely(v > t)) {
 403                 s8 overstep = t >> 1;
 404
 405                 node_page_state_add(v + overstep, pgdat, item);
 406                 __this_cpu_write(*p, -overstep);
 407         }
 408 }
 409
 410 void __inc_zone_page_state(struct page *page, enum zone_stat_item item)
 411 {
 412         __inc_zone_state(page_zone(page), item);
 413 }
 414 EXPORT_SYMBOL(__inc_zone_page_state);
 415
 416 void __inc_node_page_state(struct page *page, enum node_stat_item item)
 417 {
 418         __inc_node_state(page_pgdat(page), item);
 419 }
 420 EXPORT_SYMBOL(__inc_node_page_state);
 421
 422 void __dec_zone_state(struct zone *zone, enum zone_stat_item item)
 423 {
 424         struct per_cpu_pageset __percpu *pcp = zone->pageset;
 425         s8 __percpu *p = pcp->vm_stat_diff + item;
 426         s8 v, t;
 427
 428         v = __this_cpu_dec_return(*p);
 429         t = __this_cpu_read(pcp->stat_threshold);
 430         if (unlikely(v < - t)) {
 431                 s8 overstep = t >> 1;
 432
 433                 zone_page_state_add(v - overstep, zone, item);
 434                 __this_cpu_write(*p, overstep);
 435         }
 436 }
 437
 438 void __dec_node_state(struct pglist_data *pgdat, enum node_stat_item item)
 439 {
 440         struct per_cpu_nodestat __percpu *pcp = pgdat->per_cpu_nodestats;
 441         s8 __percpu *p = pcp->vm_node_stat_diff + item;
 442         s8 v, t;
 443
 444         v = __this_cpu_dec_return(*p);
 445         t = __this_cpu_read(pcp->stat_threshold);
 446         if (unlikely(v < - t)) {
 447                 s8 overstep = t >> 1;
 448
 449                 node_page_state_add(v - overstep, pgdat, item);
 450                 __this_cpu_write(*p, overstep);
 451         }
 452 }
 453
 454 void __dec_zone_page_state(struct page *page, enum zone_stat_item item)
 455 {
 456         __dec_zone_state(page_zone(page), item);
 457 }
 458 EXPORT_SYMBOL(__dec_zone_page_state);
 459
 460 void __dec_node_page_state(struct page *page, enum node_stat_item item)
 461 {
 462         __dec_node_state(page_pgdat(page), item);
 463 }
 464 EXPORT_SYMBOL(__dec_node_page_state);
 465
 466 #ifdef CONFIG_HAVE_CMPXCHG_LOCAL
 467 /*
 468  * If we have cmpxchg_local support then we do not need to incur the overhead
 469  * that comes with local_irq_save/restore if we use this_cpu_cmpxchg.
 470  *
 471  * mod_state() modifies the zone counter state through atomic per cpu
 472  * operations.
 473  *
 474  * Overstep mode specifies how overstep should handled:
 475  *     0       No overstepping
 476  *     1       Overstepping half of threshold
 477  *     -1      Overstepping minus half of threshold
 478 */
 479 static inline void mod_zone_state(struct zone *zone,
 480        enum zone_stat_item item, long delta, int overstep_mode)
 481 {
 482         struct per_cpu_pageset __percpu *pcp = zone->pageset;
 483         s8 __percpu *p = pcp->vm_stat_diff + item;
 484         long o, n, t, z;
 485
 486         do {
 487                 z = 0;  /* overflow to zone counters */
 488
 489                 /*
 490                  * The fetching of the stat_threshold is racy. We may apply
 491                  * a counter threshold to the wrong the cpu if we get
 492                  * rescheduled while executing here. However, the next
 493                  * counter update will apply the threshold again and
 494                  * therefore bring the counter under the threshold again.
 495                  *
 496                  * Most of the time the thresholds are the same anyways
 497                  * for all cpus in a zone.
 498                  */
 499                 t = this_cpu_read(pcp->stat_threshold);
 500
 501                 o = this_cpu_read(*p);
 502                 n = delta + o;
 503
 504                 if (n > t || n < -t) {
 505                         int os = overstep_mode * (t >> 1) ;
 506
 507                         /* Overflow must be added to zone counters */
 508                         z = n + os;
 509                         n = -os;
 510                 }
 511         } while (this_cpu_cmpxchg(*p, o, n) != o);
 512
 513         if (z)
 514                 zone_page_state_add(z, zone, item);
 515 }
 516
 517 void mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
 518                          long delta)
 519 {
 520         mod_zone_state(zone, item, delta, 0);
 521 }
 522 EXPORT_SYMBOL(mod_zone_page_state);
 523
 524 void inc_zone_page_state(struct page *page, enum zone_stat_item item)
 525 {
 526         mod_zone_state(page_zone(page), item, 1, 1);
 527 }
 528 EXPORT_SYMBOL(inc_zone_page_state);
 529
 530 void dec_zone_page_state(struct page *page, enum zone_stat_item item)
 531 {
 532         mod_zone_state(page_zone(page), item, -1, -1);
 533 }
 534 EXPORT_SYMBOL(dec_zone_page_state);
 535
 536 static inline void mod_node_state(struct pglist_data *pgdat,
 537        enum node_stat_item item, int delta, int overstep_mode)
 538 {
 539         struct per_cpu_nodestat __percpu *pcp = pgdat->per_cpu_nodestats;
 540         s8 __percpu *p = pcp->vm_node_stat_diff + item;
 541         long o, n, t, z;
 542
 543         do {
 544                 z = 0;  /* overflow to node counters */
 545
 546                 /*
 547                  * The fetching of the stat_threshold is racy. We may apply
 548                  * a counter threshold to the wrong the cpu if we get
 549                  * rescheduled while executing here. However, the next
 550                  * counter update will apply the threshold again and
 551                  * therefore bring the counter under the threshold again.
 552                  *
 553                  * Most of the time the thresholds are the same anyways
 554                  * for all cpus in a node.
 555                  */
 556                 t = this_cpu_read(pcp->stat_threshold);
 557
 558                 o = this_cpu_read(*p);
 559                 n = delta + o;
 560
 561                 if (n > t || n < -t) {
 562                         int os = overstep_mode * (t >> 1) ;
 563
 564                         /* Overflow must be added to node counters */
 565                         z = n + os;
 566                         n = -os;
 567                 }
 568         } while (this_cpu_cmpxchg(*p, o, n) != o);
 569
 570         if (z)
 571                 node_page_state_add(z, pgdat, item);
 572 }
 573
 574 void mod_node_page_state(struct pglist_data *pgdat, enum node_stat_item item,
 575                                         long delta)
 576 {
 577         mod_node_state(pgdat, item, delta, 0);
 578 }
 579 EXPORT_SYMBOL(mod_node_page_state);
 580
 581 void inc_node_state(struct pglist_data *pgdat, enum node_stat_item item)
 582 {
 583         mod_node_state(pgdat, item, 1, 1);
 584 }
 585
 586 void inc_node_page_state(struct page *page, enum node_stat_item item)
 587 {
 588         mod_node_state(page_pgdat(page), item, 1, 1);
 589 }
 590 EXPORT_SYMBOL(inc_node_page_state);
 591
 592 void dec_node_page_state(struct page *page, enum node_stat_item item)
 593 {
 594         mod_node_state(page_pgdat(page), item, -1, -1);
 595 }
 596 EXPORT_SYMBOL(dec_node_page_state);
 597 #else
 598 /*
 599  * Use interrupt disable to serialize counter updates
 600  */
 601 void mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
 602                          long delta)
 603 {
 604         unsigned long flags;
 605
 606         local_irq_save(flags);
 607         __mod_zone_page_state(zone, item, delta);
 608         local_irq_restore(flags);
 609 }
 610 EXPORT_SYMBOL(mod_zone_page_state);
 611
 612 void inc_zone_page_state(struct page *page, enum zone_stat_item item)
 613 {
 614         unsigned long flags;
 615         struct zone *zone;
 616
 617         zone = page_zone(page);
 618         local_irq_save(flags);
 619         __inc_zone_state(zone, item);
 620         local_irq_restore(flags);
 621 }
 622 EXPORT_SYMBOL(inc_zone_page_state);
 623
 624 void dec_zone_page_state(struct page *page, enum zone_stat_item item)
 625 {
 626         unsigned long flags;
 627
 628         local_irq_save(flags);
 629         __dec_zone_page_state(page, item);
 630         local_irq_restore(flags);
 631 }
 632 EXPORT_SYMBOL(dec_zone_page_state);
 633
 634 void inc_node_state(struct pglist_data *pgdat, enum node_stat_item item)
 635 {
 636         unsigned long flags;
 637
 638         local_irq_save(flags);
 639         __inc_node_state(pgdat, item);
 640         local_irq_restore(flags);
 641 }
 642 EXPORT_SYMBOL(inc_node_state);
 643
 644 void mod_node_page_state(struct pglist_data *pgdat, enum node_stat_item item,
 645                                         long delta)
 646 {
 647         unsigned long flags;
 648
 649         local_irq_save(flags);
 650         __mod_node_page_state(pgdat, item, delta);
 651         local_irq_restore(flags);
 652 }
 653 EXPORT_SYMBOL(mod_node_page_state);
 654
 655 void inc_node_page_state(struct page *page, enum node_stat_item item)
 656 {
 657         unsigned long flags;
 658         struct pglist_data *pgdat;
 659
 660         pgdat = page_pgdat(page);
 661         local_irq_save(flags);
 662         __inc_node_state(pgdat, item);
 663         local_irq_restore(flags);
 664 }
 665 EXPORT_SYMBOL(inc_node_page_state);
 666
 667 void dec_node_page_state(struct page *page, enum node_stat_item item)
 668 {
 669         unsigned long flags;
 670
 671         local_irq_save(flags);
 672         __dec_node_page_state(page, item);
 673         local_irq_restore(flags);
 674 }
 675 EXPORT_SYMBOL(dec_node_page_state);
 676 #endif
 677
 678 /*
 679  * Fold a differential into the global counters.
 680  * Returns the number of counters updated.
 681  */
 682 #ifdef CONFIG_NUMA
 683 static int fold_diff(int *zone_diff, int *numa_diff, int *node_diff)
 684 {
 685         int i;
 686         int changes = 0;
 687
 688         for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
 689                 if (zone_diff[i]) {
 690                         atomic_long_add(zone_diff[i], &vm_zone_stat[i]);
 691                         changes++;
 692         }
 693
 694         for (i = 0; i < NR_VM_NUMA_STAT_ITEMS; i++)
 695                 if (numa_diff[i]) {
 696                         atomic_long_add(numa_diff[i], &vm_numa_stat[i]);
 697                         changes++;
 698         }
 699
 700         for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++)
 701                 if (node_diff[i]) {
 702                         atomic_long_add(node_diff[i], &vm_node_stat[i]);
 703                         changes++;
 704         }
 705         return changes;
 706 }
 707 #else
 708 static int fold_diff(int *zone_diff, int *node_diff)
 709 {
 710         int i;
 711         int changes = 0;
 712
 713         for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
 714                 if (zone_diff[i]) {
 715                         atomic_long_add(zone_diff[i], &vm_zone_stat[i]);
 716                         changes++;
 717         }
 718
 719         for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++)
 720                 if (node_diff[i]) {
 721                         atomic_long_add(node_diff[i], &vm_node_stat[i]);
 722                         changes++;
 723         }
 724         return changes;
 725 }
 726 #endif /* CONFIG_NUMA */
 727
 728 /*
 729  * Update the zone counters for the current cpu.
 730  *
 731  * Note that refresh_cpu_vm_stats strives to only access
 732  * node local memory. The per cpu pagesets on remote zones are placed
 733  * in the memory local to the processor using that pageset. So the
 734  * loop over all zones will access a series of cachelines local to
 735  * the processor.
 736  *
 737  * The call to zone_page_state_add updates the cachelines with the
 738  * statistics in the remote zone struct as well as the global cachelines
 739  * with the global counters. These could cause remote node cache line
 740  * bouncing and will have to be only done when necessary.
 741  *
 742  * The function returns the number of global counters updated.
 743  */
 744 static int refresh_cpu_vm_stats(bool do_pagesets)
 745 {
 746         struct pglist_data *pgdat;
 747         struct zone *zone;
 748         int i;
 749         int global_zone_diff[NR_VM_ZONE_STAT_ITEMS] = { 0, };
 750 #ifdef CONFIG_NUMA
 751         int global_numa_diff[NR_VM_NUMA_STAT_ITEMS] = { 0, };
 752 #endif
 753         int global_node_diff[NR_VM_NODE_STAT_ITEMS] = { 0, };
 754         int changes = 0;
 755
 756         for_each_populated_zone(zone) {
 757                 struct per_cpu_pageset __percpu *p = zone->pageset;
 758
 759                 for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++) {
 760                         int v;
 761
 762                         v = this_cpu_xchg(p->vm_stat_diff[i], 0);
 763                         if (v) {
 764
 765                                 atomic_long_add(v, &zone->vm_stat[i]);
 766                                 global_zone_diff[i] += v;
 767 #ifdef CONFIG_NUMA
 768                                 /* 3 seconds idle till flush */
 769                                 __this_cpu_write(p->expire, 3);
 770 #endif
 771                         }
 772                 }
 773 #ifdef CONFIG_NUMA
 774                 for (i = 0; i < NR_VM_NUMA_STAT_ITEMS; i++) {
 775                         int v;
 776
 777                         v = this_cpu_xchg(p->vm_numa_stat_diff[i], 0);
 778                         if (v) {
 779
 780                                 atomic_long_add(v, &zone->vm_numa_stat[i]);
 781                                 global_numa_diff[i] += v;
 782                                 __this_cpu_write(p->expire, 3);
 783                         }
 784                 }
 785
 786                 if (do_pagesets) {
 787                         cond_resched();
 788                         /*
 789                          * Deal with draining the remote pageset of this
 790                          * processor
 791                          *
 792                          * Check if there are pages remaining in this pageset
 793                          * if not then there is nothing to expire.
 794                          */
 795                         if (!__this_cpu_read(p->expire) ||
 796                                !__this_cpu_read(p->pcp.count))
 797                                 continue;
 798
 799                         /*
 800                          * We never drain zones local to this processor.
 801                          */
 802                         if (zone_to_nid(zone) == numa_node_id()) {
 803                                 __this_cpu_write(p->expire, 0);
 804                                 continue;
 805                         }
 806
 807                         if (__this_cpu_dec_return(p->expire))
 808                                 continue;
 809
 810                         if (__this_cpu_read(p->pcp.count)) {
 811                                 drain_zone_pages(zone, this_cpu_ptr(&p->pcp));
 812                                 changes++;
 813                         }
 814                 }
 815 #endif
 816         }
 817
 818         for_each_online_pgdat(pgdat) {
 819                 struct per_cpu_nodestat __percpu *p = pgdat->per_cpu_nodestats;
 820
 821                 for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++) {
 822                         int v;
 823
 824                         v = this_cpu_xchg(p->vm_node_stat_diff[i], 0);
 825                         if (v) {
 826                                 atomic_long_add(v, &pgdat->vm_stat[i]);
 827                                 global_node_diff[i] += v;
 828                         }
 829                 }
 830         }
 831
 832 #ifdef CONFIG_NUMA
 833         changes += fold_diff(global_zone_diff, global_numa_diff,
 834                              global_node_diff);
 835 #else
 836         changes += fold_diff(global_zone_diff, global_node_diff);
 837 #endif
 838         return changes;
 839 }
 840
 841 /*
 842  * Fold the data for an offline cpu into the global array.
 843  * There cannot be any access by the offline cpu and therefore
 844  * synchronization is simplified.
 845  */
 846 void cpu_vm_stats_fold(int cpu)
 847 {
 848         struct pglist_data *pgdat;
 849         struct zone *zone;
 850         int i;
 851         int global_zone_diff[NR_VM_ZONE_STAT_ITEMS] = { 0, };
 852 #ifdef CONFIG_NUMA
 853         int global_numa_diff[NR_VM_NUMA_STAT_ITEMS] = { 0, };
 854 #endif
 855         int global_node_diff[NR_VM_NODE_STAT_ITEMS] = { 0, };
 856
 857         for_each_populated_zone(zone) {
 858                 struct per_cpu_pageset *p;
 859
 860                 p = per_cpu_ptr(zone->pageset, cpu);
 861
 862                 for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
 863                         if (p->vm_stat_diff[i]) {
 864                                 int v;
 865
 866                                 v = p->vm_stat_diff[i];
 867                                 p->vm_stat_diff[i] = 0;
 868                                 atomic_long_add(v, &zone->vm_stat[i]);
 869                                 global_zone_diff[i] += v;
 870                         }
 871
 872 #ifdef CONFIG_NUMA
 873                 for (i = 0; i < NR_VM_NUMA_STAT_ITEMS; i++)
 874                         if (p->vm_numa_stat_diff[i]) {
 875                                 int v;
 876
 877                                 v = p->vm_numa_stat_diff[i];
 878                                 p->vm_numa_stat_diff[i] = 0;
 879                                 atomic_long_add(v, &zone->vm_numa_stat[i]);
 880                                 global_numa_diff[i] += v;
 881                         }
 882 #endif
 883         }
 884
 885         for_each_online_pgdat(pgdat) {
 886                 struct per_cpu_nodestat *p;
 887
 888                 p = per_cpu_ptr(pgdat->per_cpu_nodestats, cpu);
 889
 890                 for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++)
 891                         if (p->vm_node_stat_diff[i]) {
 892                                 int v;
 893
 894                                 v = p->vm_node_stat_diff[i];
 895                                 p->vm_node_stat_diff[i] = 0;
 896                                 atomic_long_add(v, &pgdat->vm_stat[i]);
 897                                 global_node_diff[i] += v;
 898                         }
 899         }
 900
 901 #ifdef CONFIG_NUMA
 902         fold_diff(global_zone_diff, global_numa_diff, global_node_diff);
 903 #else
 904         fold_diff(global_zone_diff, global_node_diff);
 905 #endif
 906 }
 907
 908 /*
 909  * this is only called if !populated_zone(zone), which implies no other users of
 910  * pset->vm_stat_diff[] exsist.
 911  */
 912 void drain_zonestat(struct zone *zone, struct per_cpu_pageset *pset)
 913 {
 914         int i;
 915
 916         for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
 917                 if (pset->vm_stat_diff[i]) {
 918                         int v = pset->vm_stat_diff[i];
 919                         pset->vm_stat_diff[i] = 0;
 920                         atomic_long_add(v, &zone->vm_stat[i]);
 921                         atomic_long_add(v, &vm_zone_stat[i]);
 922                 }
 923
 924 #ifdef CONFIG_NUMA
 925         for (i = 0; i < NR_VM_NUMA_STAT_ITEMS; i++)
 926                 if (pset->vm_numa_stat_diff[i]) {
 927                         int v = pset->vm_numa_stat_diff[i];
 928
 929                         pset->vm_numa_stat_diff[i] = 0;
 930                         atomic_long_add(v, &zone->vm_numa_stat[i]);
 931                         atomic_long_add(v, &vm_numa_stat[i]);
 932                 }
 933 #endif
 934 }
 935 #endif
 936
 937 #ifdef CONFIG_NUMA
 938 void __inc_numa_state(struct zone *zone,
 939                                  enum numa_stat_item item)
 940 {
 941         struct per_cpu_pageset __percpu *pcp = zone->pageset;
 942         u16 __percpu *p = pcp->vm_numa_stat_diff + item;
 943         u16 v;
 944
 945         v = __this_cpu_inc_return(*p);
 946
 947         if (unlikely(v > NUMA_STATS_THRESHOLD)) {
 948                 zone_numa_state_add(v, zone, item);
 949                 __this_cpu_write(*p, 0);
 950         }
 951 }
 952
 953 /*
 954  * Determine the per node value of a stat item. This function
 955  * is called frequently in a NUMA machine, so try to be as
 956  * frugal as possible.
 957  */
 958 unsigned long sum_zone_node_page_state(int node,
 959                                  enum zone_stat_item item)
 960 {
 961         struct zone *zones = NODE_DATA(node)->node_zones;
 962         int i;
 963         unsigned long count = 0;
 964
 965         for (i = 0; i < MAX_NR_ZONES; i++)
 966                 count += zone_page_state(zones + i, item);
 967
 968         return count;
 969 }
 970
 971 /*
 972  * Determine the per node value of a numa stat item. To avoid deviation,
 973  * the per cpu stat number in vm_numa_stat_diff[] is also included.
 974  */
 975 unsigned long sum_zone_numa_state(int node,
 976                                  enum numa_stat_item item)
 977 {
 978         struct zone *zones = NODE_DATA(node)->node_zones;
 979         int i;
 980         unsigned long count = 0;
 981
 982         for (i = 0; i < MAX_NR_ZONES; i++)
 983                 count += zone_numa_state_snapshot(zones + i, item);
 984
 985         return count;
 986 }
 987
 988 /*
 989  * Determine the per node value of a stat item.
 990  */
 991 unsigned long node_page_state(struct pglist_data *pgdat,
 992                                 enum node_stat_item item)
 993 {
 994         long x = atomic_long_read(&pgdat->vm_stat[item]);
 995 #ifdef CONFIG_SMP
 996         if (x < 0)
 997                 x = 0;
 998 #endif
 999         return x;
1000 }
1001 #endif
1002
1003 #ifdef CONFIG_COMPACTION
1004
1005 struct contig_page_info {
1006         unsigned long free_pages;
1007         unsigned long free_blocks_total;
1008         unsigned long free_blocks_suitable;
1009 };
1010
1011 /*
1012  * Calculate the number of free pages in a zone, how many contiguous
1013  * pages are free and how many are large enough to satisfy an allocation of
1014  * the target size. Note that this function makes no attempt to estimate
1015  * how many suitable free blocks there *might* be if MOVABLE pages were
1016  * migrated. Calculating that is possible, but expensive and can be
1017  * figured out from userspace
1018  */
1019 static void fill_contig_page_info(struct zone *zone,
1020                                 unsigned int suitable_order,
1021                                 struct contig_page_info *info)
1022 {
1023         unsigned int order;
1024
1025         info->free_pages = 0;
1026         info->free_blocks_total = 0;
1027         info->free_blocks_suitable = 0;
1028
1029         for (order = 0; order < MAX_ORDER; order++) {
1030                 unsigned long blocks;
1031
1032                 /* Count number of free blocks */
1033                 blocks = zone->free_area[order].nr_free;
1034                 info->free_blocks_total += blocks;
1035
1036                 /* Count free base pages */
1037                 info->free_pages += blocks << order;
1038
1039                 /* Count the suitable free blocks */
1040                 if (order >= suitable_order)
1041                         info->free_blocks_suitable += blocks <<
1042                                                 (order - suitable_order);
1043         }
1044 }
1045
1046 /*
1047  * A fragmentation index only makes sense if an allocation of a requested
1048  * size would fail. If that is true, the fragmentation index indicates
1049  * whether external fragmentation or a lack of memory was the problem.
1050  * The value can be used to determine if page reclaim or compaction
1051  * should be used
1052  */
1053 static int __fragmentation_index(unsigned int order, struct contig_page_info *info)
1054 {
1055         unsigned long requested = 1UL << order;
1056
1057         if (WARN_ON_ONCE(order >= MAX_ORDER))
1058                 return 0;
1059
1060         if (!info->free_blocks_total)
1061                 return 0;
1062
1063         /* Fragmentation index only makes sense when a request would fail */
1064         if (info->free_blocks_suitable)
1065                 return -1000;
1066
1067         /*
1068          * Index is between 0 and 1 so return within 3 decimal places
1069          *
1070          * 0 => allocation would fail due to lack of memory
1071          * 1 => allocation would fail due to fragmentation
1072          */
1073         return 1000 - div_u64( (1000+(div_u64(info->free_pages * 1000ULL, requested))), info->free_blocks_total);
1074 }
1075
1076 /* Same as __fragmentation index but allocs contig_page_info on stack */
1077 int fragmentation_index(struct zone *zone, unsigned int order)
1078 {
1079         struct contig_page_info info;
1080
1081         fill_contig_page_info(zone, order, &info);
1082         return __fragmentation_index(order, &info);
1083 }
1084 #endif
1085
1086 #if defined(CONFIG_PROC_FS) || defined(CONFIG_SYSFS) || defined(CONFIG_NUMA)
1087 #ifdef CONFIG_ZONE_DMA
1088 #define TEXT_FOR_DMA(xx) xx "_dma",
1089 #else
1090 #define TEXT_FOR_DMA(xx)
1091 #endif
1092
1093 #ifdef CONFIG_ZONE_DMA32
1094 #define TEXT_FOR_DMA32(xx) xx "_dma32",
1095 #else
1096 #define TEXT_FOR_DMA32(xx)
1097 #endif
1098
1099 #ifdef CONFIG_HIGHMEM
1100 #define TEXT_FOR_HIGHMEM(xx) xx "_high",
1101 #else
1102 #define TEXT_FOR_HIGHMEM(xx)
1103 #endif
1104
1105 #define TEXTS_FOR_ZONES(xx) TEXT_FOR_DMA(xx) TEXT_FOR_DMA32(xx) xx "_normal", \
1106                                         TEXT_FOR_HIGHMEM(xx) xx "_movable",
1107
1108 const char * const vmstat_text[] = {
1109         /* enum zone_stat_item countes */
1110         "nr_free_pages",
1111         "nr_zone_inactive_anon",
1112         "nr_zone_active_anon",
1113         "nr_zone_inactive_file",
1114         "nr_zone_active_file",
1115         "nr_zone_unevictable",
1116         "nr_zone_write_pending",
1117         "nr_mlock",
1118         "nr_page_table_pages",
1119         "nr_kernel_stack",
1120         "nr_bounce",
1121 #if IS_ENABLED(CONFIG_ZSMALLOC)
1122         "nr_zspages",
1123 #endif
1124         "nr_free_cma",
1125
1126         /* enum numa_stat_item counters */
1127 #ifdef CONFIG_NUMA
1128         "numa_hit",
1129         "numa_miss",
1130         "numa_foreign",
1131         "numa_interleave",
1132         "numa_local",
1133         "numa_other",
1134 #endif
1135
1136         /* Node-based counters */
1137         "nr_inactive_anon",
1138         "nr_active_anon",
1139         "nr_inactive_file",
1140         "nr_active_file",
1141         "nr_unevictable",
1142         "nr_slab_reclaimable",
1143         "nr_slab_unreclaimable",
1144         "nr_isolated_anon",
1145         "nr_isolated_file",
1146         "workingset_nodes",
1147         "workingset_refault",
1148         "workingset_activate",
1149         "workingset_restore",
1150         "workingset_nodereclaim",
1151         "nr_anon_pages",
1152         "nr_mapped",
1153         "nr_file_pages",
1154         "nr_dirty",
1155         "nr_writeback",
1156         "nr_writeback_temp",
1157         "nr_shmem",
1158         "nr_shmem_hugepages",
1159         "nr_shmem_pmdmapped",
1160         "nr_anon_transparent_hugepages",
1161         "nr_unstable",
1162         "nr_vmscan_write",
1163         "nr_vmscan_immediate_reclaim",
1164         "nr_dirtied",
1165         "nr_written",
1166         "nr_kernel_misc_reclaimable",
1167
1168         /* enum writeback_stat_item counters */
1169         "nr_dirty_threshold",
1170         "nr_dirty_background_threshold",
1171
1172 #ifdef CONFIG_VM_EVENT_COUNTERS
1173         /* enum vm_event_item counters */
1174         "pgpgin",
1175         "pgpgout",
1176         "pswpin",
1177         "pswpout",
1178
1179         TEXTS_FOR_ZONES("pgalloc")
1180         TEXTS_FOR_ZONES("allocstall")
1181         TEXTS_FOR_ZONES("pgskip")
1182
1183         "pgfree",
1184         "pgactivate",
1185         "pgdeactivate",
1186         "pglazyfree",
1187
1188         "pgfault",
1189         "pgmajfault",
1190         "pglazyfreed",
1191
1192         "pgrefill",
1193         "pgsteal_kswapd",
1194         "pgsteal_direct",
1195         "pgscan_kswapd",
1196         "pgscan_direct",
1197         "pgscan_direct_throttle",
1198
1199 #ifdef CONFIG_NUMA
1200         "zone_reclaim_failed",
1201 #endif
1202         "pginodesteal",
1203         "slabs_scanned",
1204         "kswapd_inodesteal",
1205         "kswapd_low_wmark_hit_quickly",
1206         "kswapd_high_wmark_hit_quickly",
1207         "pageoutrun",
1208
1209         "pgrotated",
1210
1211         "drop_pagecache",
1212         "drop_slab",
1213         "oom_kill",
1214
1215 #ifdef CONFIG_NUMA_BALANCING
1216         "numa_pte_updates",
1217         "numa_huge_pte_updates",
1218         "numa_hint_faults",
1219         "numa_hint_faults_local",
1220         "numa_pages_migrated",
1221 #endif
1222 #ifdef CONFIG_MIGRATION
1223         "pgmigrate_success",
1224         "pgmigrate_fail",
1225 #endif
1226 #ifdef CONFIG_COMPACTION
1227         "compact_migrate_scanned",
1228         "compact_free_scanned",
1229         "compact_isolated",
1230         "compact_stall",
1231         "compact_fail",
1232         "compact_success",
1233         "compact_daemon_wake",
1234         "compact_daemon_migrate_scanned",
1235         "compact_daemon_free_scanned",
1236 #endif
1237
1238 #ifdef CONFIG_HUGETLB_PAGE
1239         "htlb_buddy_alloc_success",
1240         "htlb_buddy_alloc_fail",
1241 #endif
1242         "unevictable_pgs_culled",
1243         "unevictable_pgs_scanned",
1244         "unevictable_pgs_rescued",
1245         "unevictable_pgs_mlocked",
1246         "unevictable_pgs_munlocked",
1247         "unevictable_pgs_cleared",
1248         "unevictable_pgs_stranded",
1249
1250 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
1251         "thp_fault_alloc",
1252         "thp_fault_fallback",
1253         "thp_collapse_alloc",
1254         "thp_collapse_alloc_failed",
1255         "thp_file_alloc",
1256         "thp_file_mapped",
1257         "thp_split_page",
1258         "thp_split_page_failed",
1259         "thp_deferred_split_page",
1260         "thp_split_pmd",
1261 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1262         "thp_split_pud",
1263 #endif
1264         "thp_zero_page_alloc",
1265         "thp_zero_page_alloc_failed",
1266         "thp_swpout",
1267         "thp_swpout_fallback",
1268 #endif
1269 #ifdef CONFIG_MEMORY_BALLOON
1270         "balloon_inflate",
1271         "balloon_deflate",
1272 #ifdef CONFIG_BALLOON_COMPACTION
1273         "balloon_migrate",
1274 #endif
1275 #endif /* CONFIG_MEMORY_BALLOON */
1276 #ifdef CONFIG_DEBUG_TLBFLUSH
1277 #ifdef CONFIG_SMP
1278         "nr_tlb_remote_flush",
1279         "nr_tlb_remote_flush_received",
1280 #else
1281         "", /* nr_tlb_remote_flush */
1282         "", /* nr_tlb_remote_flush_received */
1283 #endif /* CONFIG_SMP */
1284         "nr_tlb_local_flush_all",
1285         "nr_tlb_local_flush_one",
1286 #endif /* CONFIG_DEBUG_TLBFLUSH */
1287
1288 #ifdef CONFIG_DEBUG_VM_VMACACHE
1289         "vmacache_find_calls",
1290         "vmacache_find_hits",
1291 #endif
1292 #ifdef CONFIG_SWAP
1293         "swap_ra",
1294         "swap_ra_hit",
1295 #endif
1296 #endif /* CONFIG_VM_EVENTS_COUNTERS */
1297 };
1298 #endif /* CONFIG_PROC_FS || CONFIG_SYSFS || CONFIG_NUMA */
1299
1300 #if (defined(CONFIG_DEBUG_FS) && defined(CONFIG_COMPACTION)) || \
1301      defined(CONFIG_PROC_FS)
1302 static void *frag_start(struct seq_file *m, loff_t *pos)
1303 {
1304         pg_data_t *pgdat;
1305         loff_t node = *pos;
1306
1307         for (pgdat = first_online_pgdat();
1308              pgdat && node;
1309              pgdat = next_online_pgdat(pgdat))
1310                 --node;
1311
1312         return pgdat;
1313 }
1314
1315 static void *frag_next(struct seq_file *m, void *arg, loff_t *pos)
1316 {
1317         pg_data_t *pgdat = (pg_data_t *)arg;
1318
1319         (*pos)++;
1320         return next_online_pgdat(pgdat);
1321 }
1322
1323 static void frag_stop(struct seq_file *m, void *arg)
1324 {
1325 }
1326
1327 /*
1328  * Walk zones in a node and print using a callback.
1329  * If @assert_populated is true, only use callback for zones that are populated.
1330  */
1331 static void walk_zones_in_node(struct seq_file *m, pg_data_t *pgdat,
1332                 bool assert_populated, bool nolock,
1333                 void (*print)(struct seq_file *m, pg_data_t *, struct zone *))
1334 {
1335         struct zone *zone;
1336         struct zone *node_zones = pgdat->node_zones;
1337         unsigned long flags;
1338
1339         for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
1340                 if (assert_populated && !populated_zone(zone))
1341                         continue;
1342
1343                 if (!nolock)
1344                         spin_lock_irqsave(&zone->lock, flags);
1345                 print(m, pgdat, zone);
1346                 if (!nolock)
1347                         spin_unlock_irqrestore(&zone->lock, flags);
1348         }
1349 }
1350 #endif
1351
1352 #ifdef CONFIG_PROC_FS
1353 static void frag_show_print(struct seq_file *m, pg_data_t *pgdat,
1354                                                 struct zone *zone)
1355 {
1356         int order;
1357
1358         seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
1359         for (order = 0; order < MAX_ORDER; ++order)
1360                 seq_printf(m, "%6lu ", zone->free_area[order].nr_free);
1361         seq_putc(m, '\n');
1362 }
1363
1364 /*
1365  * This walks the free areas for each zone.
1366  */
1367 static int frag_show(struct seq_file *m, void *arg)
1368 {
1369         pg_data_t *pgdat = (pg_data_t *)arg;
1370         walk_zones_in_node(m, pgdat, true, false, frag_show_print);
1371         return 0;
1372 }
1373
1374 static void pagetypeinfo_showfree_print(struct seq_file *m,
1375                                         pg_data_t *pgdat, struct zone *zone)
1376 {
1377         int order, mtype;
1378
1379         for (mtype = 0; mtype < MIGRATE_TYPES; mtype++) {
1380                 seq_printf(m, "Node %4d, zone %8s, type %12s ",
1381                                         pgdat->node_id,
1382                                         zone->name,
1383                                         migratetype_names[mtype]);
1384                 for (order = 0; order < MAX_ORDER; ++order) {
1385                         unsigned long freecount = 0;
1386                         struct free_area *area;
1387                         struct list_head *curr;
1388
1389                         area = &(zone->free_area[order]);
1390
1391                         list_for_each(curr, &area->free_list[mtype])
1392                                 freecount++;
1393                         seq_printf(m, "%6lu ", freecount);
1394                 }
1395                 seq_putc(m, '\n');
1396         }
1397 }
1398
1399 /* Print out the free pages at each order for each migatetype */
1400 static int pagetypeinfo_showfree(struct seq_file *m, void *arg)
1401 {
1402         int order;
1403         pg_data_t *pgdat = (pg_data_t *)arg;
1404
1405         /* Print header */
1406         seq_printf(m, "%-43s ", "Free pages count per migrate type at order");
1407         for (order = 0; order < MAX_ORDER; ++order)
1408                 seq_printf(m, "%6d ", order);
1409         seq_putc(m, '\n');
1410
1411         walk_zones_in_node(m, pgdat, true, false, pagetypeinfo_showfree_print);
1412
1413         return 0;
1414 }
1415
1416 static void pagetypeinfo_showblockcount_print(struct seq_file *m,
1417                                         pg_data_t *pgdat, struct zone *zone)
1418 {
1419         int mtype;
1420         unsigned long pfn;
1421         unsigned long start_pfn = zone->zone_start_pfn;
1422         unsigned long end_pfn = zone_end_pfn(zone);
1423         unsigned long count[MIGRATE_TYPES] = { 0, };
1424
1425         for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
1426                 struct page *page;
1427
1428                 page = pfn_to_online_page(pfn);
1429                 if (!page)
1430                         continue;
1431
1432                 /* Watch for unexpected holes punched in the memmap */
1433                 if (!memmap_valid_within(pfn, page, zone))
1434                         continue;
1435
1436                 if (page_zone(page) != zone)
1437                         continue;
1438
1439                 mtype = get_pageblock_migratetype(page);
1440
1441                 if (mtype < MIGRATE_TYPES)
1442                         count[mtype]++;
1443         }
1444
1445         /* Print counts */
1446         seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
1447         for (mtype = 0; mtype < MIGRATE_TYPES; mtype++)
1448                 seq_printf(m, "%12lu ", count[mtype]);
1449         seq_putc(m, '\n');
1450 }
1451
1452 /* Print out the number of pageblocks for each migratetype */
1453 static int pagetypeinfo_showblockcount(struct seq_file *m, void *arg)
1454 {
1455         int mtype;
1456         pg_data_t *pgdat = (pg_data_t *)arg;
1457
1458         seq_printf(m, "\n%-23s", "Number of blocks type ");
1459         for (mtype = 0; mtype < MIGRATE_TYPES; mtype++)
1460                 seq_printf(m, "%12s ", migratetype_names[mtype]);
1461         seq_putc(m, '\n');
1462         walk_zones_in_node(m, pgdat, true, false,
1463                 pagetypeinfo_showblockcount_print);
1464
1465         return 0;
1466 }
1467
1468 /*
1469  * Print out the number of pageblocks for each migratetype that contain pages
1470  * of other types. This gives an indication of how well fallbacks are being
1471  * contained by rmqueue_fallback(). It requires information from PAGE_OWNER
1472  * to determine what is going on
1473  */
1474 static void pagetypeinfo_showmixedcount(struct seq_file *m, pg_data_t *pgdat)
1475 {
1476 #ifdef CONFIG_PAGE_OWNER
1477         int mtype;
1478
1479         if (!static_branch_unlikely(&page_owner_inited))
1480                 return;
1481
1482         drain_all_pages(NULL);
1483
1484         seq_printf(m, "\n%-23s", "Number of mixed blocks ");
1485         for (mtype = 0; mtype < MIGRATE_TYPES; mtype++)
1486                 seq_printf(m, "%12s ", migratetype_names[mtype]);
1487         seq_putc(m, '\n');
1488
1489         walk_zones_in_node(m, pgdat, true, true,
1490                 pagetypeinfo_showmixedcount_print);
1491 #endif /* CONFIG_PAGE_OWNER */
1492 }
1493
1494 /*
1495  * This prints out statistics in relation to grouping pages by mobility.
1496  * It is expensive to collect so do not constantly read the file.
1497  */
1498 static int pagetypeinfo_show(struct seq_file *m, void *arg)
1499 {
1500         pg_data_t *pgdat = (pg_data_t *)arg;
1501
1502         /* check memoryless node */
1503         if (!node_state(pgdat->node_id, N_MEMORY))
1504                 return 0;
1505
1506         seq_printf(m, "Page block order: %d\n", pageblock_order);
1507         seq_printf(m, "Pages per block:  %lu\n", pageblock_nr_pages);
1508         seq_putc(m, '\n');
1509         pagetypeinfo_showfree(m, pgdat);
1510         pagetypeinfo_showblockcount(m, pgdat);
1511         pagetypeinfo_showmixedcount(m, pgdat);
1512
1513         return 0;
1514 }
1515
1516 static const struct seq_operations fragmentation_op = {
1517         .start  = frag_start,
1518         .next   = frag_next,
1519         .stop   = frag_stop,
1520         .show   = frag_show,
1521 };
1522
1523 static const struct seq_operations pagetypeinfo_op = {
1524         .start  = frag_start,
1525         .next   = frag_next,
1526         .stop   = frag_stop,
1527         .show   = pagetypeinfo_show,
1528 };
1529
1530 static bool is_zone_first_populated(pg_data_t *pgdat, struct zone *zone)
1531 {
1532         int zid;
1533
1534         for (zid = 0; zid < MAX_NR_ZONES; zid++) {
1535                 struct zone *compare = &pgdat->node_zones[zid];
1536
1537                 if (populated_zone(compare))
1538                         return zone == compare;
1539         }
1540
1541         return false;
1542 }
1543
1544 static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
1545                                                         struct zone *zone)
1546 {
1547         int i;
1548         seq_printf(m, "Node %d, zone %8s", pgdat->node_id, zone->name);
1549         if (is_zone_first_populated(pgdat, zone)) {
1550                 seq_printf(m, "\n  per-node stats");
1551                 for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++) {
1552                         seq_printf(m, "\n      %-12s %lu",
1553                                 vmstat_text[i + NR_VM_ZONE_STAT_ITEMS +
1554                                 NR_VM_NUMA_STAT_ITEMS],
1555                                 node_page_state(pgdat, i));
1556                 }
1557         }
1558         seq_printf(m,
1559                    "\n  pages free     %lu"
1560                    "\n        min      %lu"
1561                    "\n        low      %lu"
1562                    "\n        high     %lu"
1563                    "\n        spanned  %lu"
1564                    "\n        present  %lu"
1565                    "\n        managed  %lu",
1566                    zone_page_state(zone, NR_FREE_PAGES),
1567                    min_wmark_pages(zone),
1568                    low_wmark_pages(zone),
1569                    high_wmark_pages(zone),
1570                    zone->spanned_pages,
1571                    zone->present_pages,
1572                    zone->managed_pages);
1573
1574         seq_printf(m,
1575                    "\n        protection: (%ld",
1576                    zone->lowmem_reserve[0]);
1577         for (i = 1; i < ARRAY_SIZE(zone->lowmem_reserve); i++)
1578                 seq_printf(m, ", %ld", zone->lowmem_reserve[i]);
1579         seq_putc(m, ')');
1580
1581         /* If unpopulated, no other information is useful */
1582         if (!populated_zone(zone)) {
1583                 seq_putc(m, '\n');
1584                 return;
1585         }
1586
1587         for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
1588                 seq_printf(m, "\n      %-12s %lu", vmstat_text[i],
1589                                 zone_page_state(zone, i));
1590
1591 #ifdef CONFIG_NUMA
1592         for (i = 0; i < NR_VM_NUMA_STAT_ITEMS; i++)
1593                 seq_printf(m, "\n      %-12s %lu",
1594                                 vmstat_text[i + NR_VM_ZONE_STAT_ITEMS],
1595                                 zone_numa_state_snapshot(zone, i));
1596 #endif
1597
1598         seq_printf(m, "\n  pagesets");
1599         for_each_online_cpu(i) {
1600                 struct per_cpu_pageset *pageset;
1601
1602                 pageset = per_cpu_ptr(zone->pageset, i);
1603                 seq_printf(m,
1604                            "\n    cpu: %i"
1605                            "\n              count: %i"
1606                            "\n              high:  %i"
1607                            "\n              batch: %i",
1608                            i,
1609                            pageset->pcp.count,
1610                            pageset->pcp.high,
1611                            pageset->pcp.batch);
1612 #ifdef CONFIG_SMP
1613                 seq_printf(m, "\n  vm stats threshold: %d",
1614                                 pageset->stat_threshold);
1615 #endif
1616         }
1617         seq_printf(m,
1618                    "\n  node_unreclaimable:  %u"
1619                    "\n  start_pfn:           %lu",
1620                    pgdat->kswapd_failures >= MAX_RECLAIM_RETRIES,
1621                    zone->zone_start_pfn);
1622         seq_putc(m, '\n');
1623 }
1624
1625 /*
1626  * Output information about zones in @pgdat.  All zones are printed regardless
1627  * of whether they are populated or not: lowmem_reserve_ratio operates on the
1628  * set of all zones and userspace would not be aware of such zones if they are
1629  * suppressed here (zoneinfo displays the effect of lowmem_reserve_ratio).
1630  */
1631 static int zoneinfo_show(struct seq_file *m, void *arg)
1632 {
1633         pg_data_t *pgdat = (pg_data_t *)arg;
1634         walk_zones_in_node(m, pgdat, false, false, zoneinfo_show_print);
1635         return 0;
1636 }
1637
1638 static const struct seq_operations zoneinfo_op = {
1639         .start  = frag_start, /* iterate over all zones. The same as in
1640                                * fragmentation. */
1641         .next   = frag_next,
1642         .stop   = frag_stop,
1643         .show   = zoneinfo_show,
1644 };
1645
1646 enum writeback_stat_item {
1647         NR_DIRTY_THRESHOLD,
1648         NR_DIRTY_BG_THRESHOLD,
1649         NR_VM_WRITEBACK_STAT_ITEMS,
1650 };
1651
1652 static void *vmstat_start(struct seq_file *m, loff_t *pos)
1653 {
1654         unsigned long *v;
1655         int i, stat_items_size;
1656
1657         if (*pos >= ARRAY_SIZE(vmstat_text))
1658                 return NULL;
1659         stat_items_size = NR_VM_ZONE_STAT_ITEMS * sizeof(unsigned long) +
1660                           NR_VM_NUMA_STAT_ITEMS * sizeof(unsigned long) +
1661                           NR_VM_NODE_STAT_ITEMS * sizeof(unsigned long) +
1662                           NR_VM_WRITEBACK_STAT_ITEMS * sizeof(unsigned long);
1663
1664 #ifdef CONFIG_VM_EVENT_COUNTERS
1665         stat_items_size += sizeof(struct vm_event_state);
1666 #endif
1667
1668         BUILD_BUG_ON(stat_items_size !=
1669                      ARRAY_SIZE(vmstat_text) * sizeof(unsigned long));
1670         v = kmalloc(stat_items_size, GFP_KERNEL);
1671         m->private = v;
1672         if (!v)
1673                 return ERR_PTR(-ENOMEM);
1674         for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
1675                 v[i] = global_zone_page_state(i);
1676         v += NR_VM_ZONE_STAT_ITEMS;
1677
1678 #ifdef CONFIG_NUMA
1679         for (i = 0; i < NR_VM_NUMA_STAT_ITEMS; i++)
1680                 v[i] = global_numa_state(i);
1681         v += NR_VM_NUMA_STAT_ITEMS;
1682 #endif
1683
1684         for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++)
1685                 v[i] = global_node_page_state(i);
1686         v += NR_VM_NODE_STAT_ITEMS;
1687
1688         global_dirty_limits(v + NR_DIRTY_BG_THRESHOLD,
1689                             v + NR_DIRTY_THRESHOLD);
1690         v += NR_VM_WRITEBACK_STAT_ITEMS;
1691
1692 #ifdef CONFIG_VM_EVENT_COUNTERS
1693         all_vm_events(v);
1694         v[PGPGIN] /= 2;         /* sectors -> kbytes */
1695         v[PGPGOUT] /= 2;
1696 #endif
1697         return (unsigned long *)m->private + *pos;
1698 }
1699
1700 static void *vmstat_next(struct seq_file *m, void *arg, loff_t *pos)
1701 {
1702         (*pos)++;
1703         if (*pos >= ARRAY_SIZE(vmstat_text))
1704                 return NULL;
1705         return (unsigned long *)m->private + *pos;
1706 }
1707
1708 static int vmstat_show(struct seq_file *m, void *arg)
1709 {
1710         unsigned long *l = arg;
1711         unsigned long off = l - (unsigned long *)m->private;
1712
1713         seq_puts(m, vmstat_text[off]);
1714         seq_put_decimal_ull(m, " ", *l);
1715         seq_putc(m, '\n');
1716         return 0;
1717 }
1718
1719 static void vmstat_stop(struct seq_file *m, void *arg)
1720 {
1721         kfree(m->private);
1722         m->private = NULL;
1723 }
1724
1725 static const struct seq_operations vmstat_op = {
1726         .start  = vmstat_start,
1727         .next   = vmstat_next,
1728         .stop   = vmstat_stop,
1729         .show   = vmstat_show,
1730 };
1731 #endif /* CONFIG_PROC_FS */
1732
1733 #ifdef CONFIG_SMP
1734 static DEFINE_PER_CPU(struct delayed_work, vmstat_work);
1735 int sysctl_stat_interval __read_mostly = HZ;
1736
1737 #ifdef CONFIG_PROC_FS
1738 static void refresh_vm_stats(struct work_struct *work)
1739 {
1740         refresh_cpu_vm_stats(true);
1741 }
1742
1743 int vmstat_refresh(struct ctl_table *table, int write,
1744                    void __user *buffer, size_t *lenp, loff_t *ppos)
1745 {
1746         long val;
1747         int err;
1748         int i;
1749
1750         /*
1751          * The regular update, every sysctl_stat_interval, may come later
1752          * than expected: leaving a significant amount in per_cpu buckets.
1753          * This is particularly misleading when checking a quantity of HUGE
1754          * pages, immediately after running a test.  /proc/sys/vm/stat_refresh,
1755          * which can equally be echo'ed to or cat'ted from (by root),
1756          * can be used to update the stats just before reading them.
1757          *
1758          * Oh, and since global_zone_page_state() etc. are so careful to hide
1759          * transiently negative values, report an error here if any of
1760          * the stats is negative, so we know to go looking for imbalance.
1761          */
1762         err = schedule_on_each_cpu(refresh_vm_stats);
1763         if (err)
1764                 return err;
1765         for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++) {
1766                 val = atomic_long_read(&vm_zone_stat[i]);
1767                 if (val < 0) {
1768                         pr_warn("%s: %s %ld\n",
1769                                 __func__, vmstat_text[i], val);
1770                         err = -EINVAL;
1771                 }
1772         }
1773 #ifdef CONFIG_NUMA
1774         for (i = 0; i < NR_VM_NUMA_STAT_ITEMS; i++) {
1775                 val = atomic_long_read(&vm_numa_stat[i]);
1776                 if (val < 0) {
1777                         pr_warn("%s: %s %ld\n",
1778                                 __func__, vmstat_text[i + NR_VM_ZONE_STAT_ITEMS], val);
1779                         err = -EINVAL;
1780                 }
1781         }
1782 #endif
1783         if (err)
1784                 return err;
1785         if (write)
1786                 *ppos += *lenp;
1787         else
1788                 *lenp = 0;
1789         return 0;
1790 }
1791 #endif /* CONFIG_PROC_FS */
1792
1793 static void vmstat_update(struct work_struct *w)
1794 {
1795         if (refresh_cpu_vm_stats(true)) {
1796                 /*
1797                  * Counters were updated so we expect more updates
1798                  * to occur in the future. Keep on running the
1799                  * update worker thread.
1800                  */
1801                 queue_delayed_work_on(smp_processor_id(), mm_percpu_wq,
1802                                 this_cpu_ptr(&vmstat_work),
1803                                 round_jiffies_relative(sysctl_stat_interval));
1804         }
1805 }
1806
1807 /*
1808  * Switch off vmstat processing and then fold all the remaining differentials
1809  * until the diffs stay at zero. The function is used by NOHZ and can only be
1810  * invoked when tick processing is not active.
1811  */
1812 /*
1813  * Check if the diffs for a certain cpu indicate that
1814  * an update is needed.
1815  */
1816 static bool need_update(int cpu)
1817 {
1818         struct zone *zone;
1819
1820         for_each_populated_zone(zone) {
1821                 struct per_cpu_pageset *p = per_cpu_ptr(zone->pageset, cpu);
1822
1823                 BUILD_BUG_ON(sizeof(p->vm_stat_diff[0]) != 1);
1824 #ifdef CONFIG_NUMA
1825                 BUILD_BUG_ON(sizeof(p->vm_numa_stat_diff[0]) != 2);
1826 #endif
1827
1828                 /*
1829                  * The fast way of checking if there are any vmstat diffs.
1830                  * This works because the diffs are byte sized items.
1831                  */
1832                 if (memchr_inv(p->vm_stat_diff, 0, NR_VM_ZONE_STAT_ITEMS))
1833                         return true;
1834 #ifdef CONFIG_NUMA
1835                 if (memchr_inv(p->vm_numa_stat_diff, 0, NR_VM_NUMA_STAT_ITEMS))
1836                         return true;
1837 #endif
1838         }
1839         return false;
1840 }
1841
1842 /*
1843  * Switch off vmstat processing and then fold all the remaining differentials
1844  * until the diffs stay at zero. The function is used by NOHZ and can only be
1845  * invoked when tick processing is not active.
1846  */
1847 void quiet_vmstat(void)
1848 {
1849         if (system_state != SYSTEM_RUNNING)
1850                 return;
1851
1852         if (!delayed_work_pending(this_cpu_ptr(&vmstat_work)))
1853                 return;
1854
1855         if (!need_update(smp_processor_id()))
1856                 return;
1857
1858         /*
1859          * Just refresh counters and do not care about the pending delayed
1860          * vmstat_update. It doesn't fire that often to matter and canceling
1861          * it would be too expensive from this path.
1862          * vmstat_shepherd will take care about that for us.
1863          */
1864         refresh_cpu_vm_stats(false);
1865 }
1866
1867 /*
1868  * Shepherd worker thread that checks the
1869  * differentials of processors that have their worker
1870  * threads for vm statistics updates disabled because of
1871  * inactivity.
1872  */
1873 static void vmstat_shepherd(struct work_struct *w);
1874
1875 static DECLARE_DEFERRABLE_WORK(shepherd, vmstat_shepherd);
1876
1877 static void vmstat_shepherd(struct work_struct *w)
1878 {
1879         int cpu;
1880
1881         get_online_cpus();
1882         /* Check processors whose vmstat worker threads have been disabled */
1883         for_each_online_cpu(cpu) {
1884                 struct delayed_work *dw = &per_cpu(vmstat_work, cpu);
1885
1886                 if (!delayed_work_pending(dw) && need_update(cpu))
1887                         queue_delayed_work_on(cpu, mm_percpu_wq, dw, 0);
1888         }
1889         put_online_cpus();
1890
1891         schedule_delayed_work(&shepherd,
1892                 round_jiffies_relative(sysctl_stat_interval));
1893 }
1894
1895 static void __init start_shepherd_timer(void)
1896 {
1897         int cpu;
1898
1899         for_each_possible_cpu(cpu)
1900                 INIT_DEFERRABLE_WORK(per_cpu_ptr(&vmstat_work, cpu),
1901                         vmstat_update);
1902
1903         schedule_delayed_work(&shepherd,
1904                 round_jiffies_relative(sysctl_stat_interval));
1905 }
1906
1907 static void __init init_cpu_node_state(void)
1908 {
1909         int node;
1910
1911         for_each_online_node(node) {
1912                 if (cpumask_weight(cpumask_of_node(node)) > 0)
1913                         node_set_state(node, N_CPU);
1914         }
1915 }
1916
1917 static int vmstat_cpu_online(unsigned int cpu)
1918 {
1919         refresh_zone_stat_thresholds();
1920         node_set_state(cpu_to_node(cpu), N_CPU);
1921         return 0;
1922 }
1923
1924 static int vmstat_cpu_down_prep(unsigned int cpu)
1925 {
1926         cancel_delayed_work_sync(&per_cpu(vmstat_work, cpu));
1927         return 0;
1928 }
1929
1930 static int vmstat_cpu_dead(unsigned int cpu)
1931 {
1932         const struct cpumask *node_cpus;
1933         int node;
1934
1935         node = cpu_to_node(cpu);
1936
1937         refresh_zone_stat_thresholds();
1938         node_cpus = cpumask_of_node(node);
1939         if (cpumask_weight(node_cpus) > 0)
1940                 return 0;
1941
1942         node_clear_state(node, N_CPU);
1943         return 0;
1944 }
1945
1946 #endif
1947
1948 struct workqueue_struct *mm_percpu_wq;
1949
1950 void __init init_mm_internals(void)
1951 {
1952         int ret __maybe_unused;
1953
1954         mm_percpu_wq = alloc_workqueue("mm_percpu_wq", WQ_MEM_RECLAIM, 0);
1955
1956 #ifdef CONFIG_SMP
1957         ret = cpuhp_setup_state_nocalls(CPUHP_MM_VMSTAT_DEAD, "mm/vmstat:dead",
1958                                         NULL, vmstat_cpu_dead);
1959         if (ret < 0)
1960                 pr_err("vmstat: failed to register 'dead' hotplug state\n");
1961
1962         ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "mm/vmstat:online",
1963                                         vmstat_cpu_online,
1964                                         vmstat_cpu_down_prep);
1965         if (ret < 0)
1966                 pr_err("vmstat: failed to register 'online' hotplug state\n");
1967
1968         get_online_cpus();
1969         init_cpu_node_state();
1970         put_online_cpus();
1971
1972         start_shepherd_timer();
1973 #endif
1974 #ifdef CONFIG_PROC_FS
1975         proc_create_seq("buddyinfo", 0444, NULL, &fragmentation_op);
1976         proc_create_seq("pagetypeinfo", 0444, NULL, &pagetypeinfo_op);
1977         proc_create_seq("vmstat", 0444, NULL, &vmstat_op);
1978         proc_create_seq("zoneinfo", 0444, NULL, &zoneinfo_op);
1979 #endif
1980 }
1981
1982 #if defined(CONFIG_DEBUG_FS) && defined(CONFIG_COMPACTION)
1983
1984 /*
1985  * Return an index indicating how much of the available free memory is
1986  * unusable for an allocation of the requested size.
1987  */
1988 static int unusable_free_index(unsigned int order,
1989                                 struct contig_page_info *info)
1990 {
1991         /* No free memory is interpreted as all free memory is unusable */
1992         if (info->free_pages == 0)
1993                 return 1000;
1994
1995         /*
1996          * Index should be a value between 0 and 1. Return a value to 3
1997          * decimal places.
1998          *
1999          * 0 => no fragmentation
2000          * 1 => high fragmentation
2001          */
2002         return div_u64((info->free_pages - (info->free_blocks_suitable << order)) * 1000ULL, info->free_pages);
2003
2004 }
2005
2006 static void unusable_show_print(struct seq_file *m,
2007                                         pg_data_t *pgdat, struct zone *zone)
2008 {
2009         unsigned int order;
2010         int index;
2011         struct contig_page_info info;
2012
2013         seq_printf(m, "Node %d, zone %8s ",
2014                                 pgdat->node_id,
2015                                 zone->name);
2016         for (order = 0; order < MAX_ORDER; ++order) {
2017                 fill_contig_page_info(zone, order, &info);
2018                 index = unusable_free_index(order, &info);
2019                 seq_printf(m, "%d.%03d ", index / 1000, index % 1000);
2020         }
2021
2022         seq_putc(m, '\n');
2023 }
2024
2025 /*
2026  * Display unusable free space index
2027  *
2028  * The unusable free space index measures how much of the available free
2029  * memory cannot be used to satisfy an allocation of a given size and is a
2030  * value between 0 and 1. The higher the value, the more of free memory is
2031  * unusable and by implication, the worse the external fragmentation is. This
2032  * can be expressed as a percentage by multiplying by 100.
2033  */
2034 static int unusable_show(struct seq_file *m, void *arg)
2035 {
2036         pg_data_t *pgdat = (pg_data_t *)arg;
2037
2038         /* check memoryless node */
2039         if (!node_state(pgdat->node_id, N_MEMORY))
2040                 return 0;
2041
2042         walk_zones_in_node(m, pgdat, true, false, unusable_show_print);
2043
2044         return 0;
2045 }
2046
2047 static const struct seq_operations unusable_op = {
2048         .start  = frag_start,
2049         .next   = frag_next,
2050         .stop   = frag_stop,
2051         .show   = unusable_show,
2052 };
2053
2054 static int unusable_open(struct inode *inode, struct file *file)
2055 {
2056         return seq_open(file, &unusable_op);
2057 }
2058
2059 static const struct file_operations unusable_file_ops = {
2060         .open           = unusable_open,
2061         .read           = seq_read,
2062         .llseek         = seq_lseek,
2063         .release        = seq_release,
2064 };
2065
2066 static void extfrag_show_print(struct seq_file *m,
2067                                         pg_data_t *pgdat, struct zone *zone)
2068 {
2069         unsigned int order;
2070         int index;
2071
2072         /* Alloc on stack as interrupts are disabled for zone walk */
2073         struct contig_page_info info;
2074
2075         seq_printf(m, "Node %d, zone %8s ",
2076                                 pgdat->node_id,
2077                                 zone->name);
2078         for (order = 0; order < MAX_ORDER; ++order) {
2079                 fill_contig_page_info(zone, order, &info);
2080                 index = __fragmentation_index(order, &info);
2081                 seq_printf(m, "%d.%03d ", index / 1000, index % 1000);
2082         }
2083
2084         seq_putc(m, '\n');
2085 }
2086
2087 /*
2088  * Display fragmentation index for orders that allocations would fail for
2089  */
2090 static int extfrag_show(struct seq_file *m, void *arg)
2091 {
2092         pg_data_t *pgdat = (pg_data_t *)arg;
2093
2094         walk_zones_in_node(m, pgdat, true, false, extfrag_show_print);
2095
2096         return 0;
2097 }
2098
2099 static const struct seq_operations extfrag_op = {
2100         .start  = frag_start,
2101         .next   = frag_next,
2102         .stop   = frag_stop,
2103         .show   = extfrag_show,
2104 };
2105
2106 static int extfrag_open(struct inode *inode, struct file *file)
2107 {
2108         return seq_open(file, &extfrag_op);
2109 }
2110
2111 static const struct file_operations extfrag_file_ops = {
2112         .open           = extfrag_open,
2113         .read           = seq_read,
2114         .llseek         = seq_lseek,
2115         .release        = seq_release,
2116 };
2117
2118 static int __init extfrag_debug_init(void)
2119 {
2120         struct dentry *extfrag_debug_root;
2121
2122         extfrag_debug_root = debugfs_create_dir("extfrag", NULL);
2123         if (!extfrag_debug_root)
2124                 return -ENOMEM;
2125
2126         if (!debugfs_create_file("unusable_index", 0444,
2127                         extfrag_debug_root, NULL, &unusable_file_ops))
2128                 goto fail;
2129
2130         if (!debugfs_create_file("extfrag_index", 0444,
2131                         extfrag_debug_root, NULL, &extfrag_file_ops))
2132                 goto fail;
2133
2134         return 0;
2135 fail:
2136         debugfs_remove_recursive(extfrag_debug_root);
2137         return -ENOMEM;
2138 }
2139
2140 module_init(extfrag_debug_init);
2141 #endif