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