mm/vmstat.c

   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  linux/mm/vmstat.c
   4  *
   5  *  Manages VM statistics
   6  *  Copyright (C) 1991, 1992, 1993, 1994  Linus Torvalds
   7  *
   8  *  zoned VM statistics
   9  *  Copyright (C) 2006 Silicon Graphics, Inc.,
  10  *              Christoph Lameter <christoph@lameter.com>
  11  *  Copyright (C) 2008-2014 Christoph Lameter
  12  */
  13 #include <linux/fs.h>
  14 #include <linux/mm.h>
  15 #include <linux/err.h>
  16 #include <linux/module.h>
  17 #include <linux/slab.h>
  18 #include <linux/cpu.h>
  19 #include <linux/cpumask.h>
  20 #include <linux/vmstat.h>
  21 #include <linux/proc_fs.h>
  22 #include <linux/seq_file.h>
  23 #include <linux/debugfs.h>
  24 #include <linux/sched.h>
  25 #include <linux/math64.h>
  26 #include <linux/writeback.h>
  27 #include <linux/compaction.h>
  28 #include <linux/mm_inline.h>
  29 #include <linux/page_owner.h>
  30 #include <linux/sched/isolation.h>
  31
  32 #include "internal.h"
  33
  34 #ifdef CONFIG_NUMA
  35 int sysctl_vm_numa_stat = ENABLE_NUMA_STAT;
  36
  37 /* zero numa counters within a zone */
  38 static void zero_zone_numa_counters(struct zone *zone)
  39 {
  40         int item, cpu;
  41
  42         for (item = 0; item < NR_VM_NUMA_EVENT_ITEMS; item++) {
  43                 atomic_long_set(&zone->vm_numa_event[item], 0);
  44                 for_each_online_cpu(cpu) {
  45                         per_cpu_ptr(zone->per_cpu_zonestats, cpu)->vm_numa_event[item]
  46                                                 = 0;
  47                 }
  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_EVENT_ITEMS; item++)
  66                 atomic_long_set(&vm_numa_event[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 *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         cpus_read_lock();
 133         sum_vm_events(ret);
 134         cpus_read_unlock();
 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_node_stat[NR_VM_NODE_STAT_ITEMS] __cacheline_aligned_in_smp;
 164 atomic_long_t vm_numa_event[NR_VM_NUMA_EVENT_ITEMS] __cacheline_aligned_in_smp;
 165 EXPORT_SYMBOL(vm_zone_stat);
 166 EXPORT_SYMBOL(vm_node_stat);
 167
 168 #ifdef CONFIG_NUMA
 169 static void fold_vm_zone_numa_events(struct zone *zone)
 170 {
 171         unsigned long zone_numa_events[NR_VM_NUMA_EVENT_ITEMS] = { 0, };
 172         int cpu;
 173         enum numa_stat_item item;
 174
 175         for_each_online_cpu(cpu) {
 176                 struct per_cpu_zonestat *pzstats;
 177
 178                 pzstats = per_cpu_ptr(zone->per_cpu_zonestats, cpu);
 179                 for (item = 0; item < NR_VM_NUMA_EVENT_ITEMS; item++)
 180                         zone_numa_events[item] += xchg(&pzstats->vm_numa_event[item], 0);
 181         }
 182
 183         for (item = 0; item < NR_VM_NUMA_EVENT_ITEMS; item++)
 184                 zone_numa_event_add(zone_numa_events[item], zone, item);
 185 }
 186
 187 void fold_vm_numa_events(void)
 188 {
 189         struct zone *zone;
 190
 191         for_each_populated_zone(zone)
 192                 fold_vm_zone_numa_events(zone);
 193 }
 194 #endif
 195
 196 #ifdef CONFIG_SMP
 197
 198 int calculate_pressure_threshold(struct zone *zone)
 199 {
 200         int threshold;
 201         int watermark_distance;
 202
 203         /*
 204          * As vmstats are not up to date, there is drift between the estimated
 205          * and real values. For high thresholds and a high number of CPUs, it
 206          * is possible for the min watermark to be breached while the estimated
 207          * value looks fine. The pressure threshold is a reduced value such
 208          * that even the maximum amount of drift will not accidentally breach
 209          * the min watermark
 210          */
 211         watermark_distance = low_wmark_pages(zone) - min_wmark_pages(zone);
 212         threshold = max(1, (int)(watermark_distance / num_online_cpus()));
 213
 214         /*
 215          * Maximum threshold is 125
 216          */
 217         threshold = min(125, threshold);
 218
 219         return threshold;
 220 }
 221
 222 int calculate_normal_threshold(struct zone *zone)
 223 {
 224         int threshold;
 225         int mem;        /* memory in 128 MB units */
 226
 227         /*
 228          * The threshold scales with the number of processors and the amount
 229          * of memory per zone. More memory means that we can defer updates for
 230          * longer, more processors could lead to more contention.
 231          * fls() is used to have a cheap way of logarithmic scaling.
 232          *
 233          * Some sample thresholds:
 234          *
 235          * Threshold    Processors      (fls)   Zonesize        fls(mem)+1
 236          * ------------------------------------------------------------------
 237          * 8            1               1       0.9-1 GB        4
 238          * 16           2               2       0.9-1 GB        4
 239          * 20           2               2       1-2 GB          5
 240          * 24           2               2       2-4 GB          6
 241          * 28           2               2       4-8 GB          7
 242          * 32           2               2       8-16 GB         8
 243          * 4            2               2       <128M           1
 244          * 30           4               3       2-4 GB          5
 245          * 48           4               3       8-16 GB         8
 246          * 32           8               4       1-2 GB          4
 247          * 32           8               4       0.9-1GB         4
 248          * 10           16              5       <128M           1
 249          * 40           16              5       900M            4
 250          * 70           64              7       2-4 GB          5
 251          * 84           64              7       4-8 GB          6
 252          * 108          512             9       4-8 GB          6
 253          * 125          1024            10      8-16 GB         8
 254          * 125          1024            10      16-32 GB        9
 255          */
 256
 257         mem = zone_managed_pages(zone) >> (27 - PAGE_SHIFT);
 258
 259         threshold = 2 * fls(num_online_cpus()) * (1 + fls(mem));
 260
 261         /*
 262          * Maximum threshold is 125
 263          */
 264         threshold = min(125, threshold);
 265
 266         return threshold;
 267 }
 268
 269 /*
 270  * Refresh the thresholds for each zone.
 271  */
 272 void refresh_zone_stat_thresholds(void)
 273 {
 274         struct pglist_data *pgdat;
 275         struct zone *zone;
 276         int cpu;
 277         int threshold;
 278
 279         /* Zero current pgdat thresholds */
 280         for_each_online_pgdat(pgdat) {
 281                 for_each_online_cpu(cpu) {
 282                         per_cpu_ptr(pgdat->per_cpu_nodestats, cpu)->stat_threshold = 0;
 283                 }
 284         }
 285
 286         for_each_populated_zone(zone) {
 287                 struct pglist_data *pgdat = zone->zone_pgdat;
 288                 unsigned long max_drift, tolerate_drift;
 289
 290                 threshold = calculate_normal_threshold(zone);
 291
 292                 for_each_online_cpu(cpu) {
 293                         int pgdat_threshold;
 294
 295                         per_cpu_ptr(zone->per_cpu_zonestats, cpu)->stat_threshold
 296                                                         = threshold;
 297
 298                         /* Base nodestat threshold on the largest populated zone. */
 299                         pgdat_threshold = per_cpu_ptr(pgdat->per_cpu_nodestats, cpu)->stat_threshold;
 300                         per_cpu_ptr(pgdat->per_cpu_nodestats, cpu)->stat_threshold
 301                                 = max(threshold, pgdat_threshold);
 302                 }
 303
 304                 /*
 305                  * Only set percpu_drift_mark if there is a danger that
 306                  * NR_FREE_PAGES reports the low watermark is ok when in fact
 307                  * the min watermark could be breached by an allocation
 308                  */
 309                 tolerate_drift = low_wmark_pages(zone) - min_wmark_pages(zone);
 310                 max_drift = num_online_cpus() * threshold;
 311                 if (max_drift > tolerate_drift)
 312                         zone->percpu_drift_mark = high_wmark_pages(zone) +
 313                                         max_drift;
 314         }
 315 }
 316
 317 void set_pgdat_percpu_threshold(pg_data_t *pgdat,
 318                                 int (*calculate_pressure)(struct zone *))
 319 {
 320         struct zone *zone;
 321         int cpu;
 322         int threshold;
 323         int i;
 324
 325         for (i = 0; i < pgdat->nr_zones; i++) {
 326                 zone = &pgdat->node_zones[i];
 327                 if (!zone->percpu_drift_mark)
 328                         continue;
 329
 330                 threshold = (*calculate_pressure)(zone);
 331                 for_each_online_cpu(cpu)
 332                         per_cpu_ptr(zone->per_cpu_zonestats, cpu)->stat_threshold
 333                                                         = threshold;
 334         }
 335 }
 336
 337 /*
 338  * For use when we know that interrupts are disabled,
 339  * or when we know that preemption is disabled and that
 340  * particular counter cannot be updated from interrupt context.
 341  */
 342 void __mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
 343                            long delta)
 344 {
 345         struct per_cpu_zonestat __percpu *pcp = zone->per_cpu_zonestats;
 346         s8 __percpu *p = pcp->vm_stat_diff + item;
 347         long x;
 348         long t;
 349
 350         /*
 351          * Accurate vmstat updates require a RMW. On !PREEMPT_RT kernels,
 352          * atomicity is provided by IRQs being disabled -- either explicitly
 353          * or via local_lock_irq. On PREEMPT_RT, local_lock_irq only disables
 354          * CPU migrations and preemption potentially corrupts a counter so
 355          * disable preemption.
 356          */
 357         preempt_disable_nested();
 358
 359         x = delta + __this_cpu_read(*p);
 360
 361         t = __this_cpu_read(pcp->stat_threshold);
 362
 363         if (unlikely(abs(x) > t)) {
 364                 zone_page_state_add(x, zone, item);
 365                 x = 0;
 366         }
 367         __this_cpu_write(*p, x);
 368
 369         preempt_enable_nested();
 370 }
 371 EXPORT_SYMBOL(__mod_zone_page_state);
 372
 373 void __mod_node_page_state(struct pglist_data *pgdat, enum node_stat_item item,
 374                                 long delta)
 375 {
 376         struct per_cpu_nodestat __percpu *pcp = pgdat->per_cpu_nodestats;
 377         s8 __percpu *p = pcp->vm_node_stat_diff + item;
 378         long x;
 379         long t;
 380
 381         if (vmstat_item_in_bytes(item)) {
 382                 /*
 383                  * Only cgroups use subpage accounting right now; at
 384                  * the global level, these items still change in
 385                  * multiples of whole pages. Store them as pages
 386                  * internally to keep the per-cpu counters compact.
 387                  */
 388                 VM_WARN_ON_ONCE(delta & (PAGE_SIZE - 1));
 389                 delta >>= PAGE_SHIFT;
 390         }
 391
 392         /* See __mod_node_page_state */
 393         preempt_disable_nested();
 394
 395         x = delta + __this_cpu_read(*p);
 396
 397         t = __this_cpu_read(pcp->stat_threshold);
 398
 399         if (unlikely(abs(x) > t)) {
 400                 node_page_state_add(x, pgdat, item);
 401                 x = 0;
 402         }
 403         __this_cpu_write(*p, x);
 404
 405         preempt_enable_nested();
 406 }
 407 EXPORT_SYMBOL(__mod_node_page_state);
 408
 409 /*
 410  * Optimized increment and decrement functions.
 411  *
 412  * These are only for a single page and therefore can take a struct page *
 413  * argument instead of struct zone *. This allows the inclusion of the code
 414  * generated for page_zone(page) into the optimized functions.
 415  *
 416  * No overflow check is necessary and therefore the differential can be
 417  * incremented or decremented in place which may allow the compilers to
 418  * generate better code.
 419  * The increment or decrement is known and therefore one boundary check can
 420  * be omitted.
 421  *
 422  * NOTE: These functions are very performance sensitive. Change only
 423  * with care.
 424  *
 425  * Some processors have inc/dec instructions that are atomic vs an interrupt.
 426  * However, the code must first determine the differential location in a zone
 427  * based on the processor number and then inc/dec the counter. There is no
 428  * guarantee without disabling preemption that the processor will not change
 429  * in between and therefore the atomicity vs. interrupt cannot be exploited
 430  * in a useful way here.
 431  */
 432 void __inc_zone_state(struct zone *zone, enum zone_stat_item item)
 433 {
 434         struct per_cpu_zonestat __percpu *pcp = zone->per_cpu_zonestats;
 435         s8 __percpu *p = pcp->vm_stat_diff + item;
 436         s8 v, t;
 437
 438         /* See __mod_node_page_state */
 439         preempt_disable_nested();
 440
 441         v = __this_cpu_inc_return(*p);
 442         t = __this_cpu_read(pcp->stat_threshold);
 443         if (unlikely(v > t)) {
 444                 s8 overstep = t >> 1;
 445
 446                 zone_page_state_add(v + overstep, zone, item);
 447                 __this_cpu_write(*p, -overstep);
 448         }
 449
 450         preempt_enable_nested();
 451 }
 452
 453 void __inc_node_state(struct pglist_data *pgdat, enum node_stat_item item)
 454 {
 455         struct per_cpu_nodestat __percpu *pcp = pgdat->per_cpu_nodestats;
 456         s8 __percpu *p = pcp->vm_node_stat_diff + item;
 457         s8 v, t;
 458
 459         VM_WARN_ON_ONCE(vmstat_item_in_bytes(item));
 460
 461         /* See __mod_node_page_state */
 462         preempt_disable_nested();
 463
 464         v = __this_cpu_inc_return(*p);
 465         t = __this_cpu_read(pcp->stat_threshold);
 466         if (unlikely(v > t)) {
 467                 s8 overstep = t >> 1;
 468
 469                 node_page_state_add(v + overstep, pgdat, item);
 470                 __this_cpu_write(*p, -overstep);
 471         }
 472
 473         preempt_enable_nested();
 474 }
 475
 476 void __inc_zone_page_state(struct page *page, enum zone_stat_item item)
 477 {
 478         __inc_zone_state(page_zone(page), item);
 479 }
 480 EXPORT_SYMBOL(__inc_zone_page_state);
 481
 482 void __inc_node_page_state(struct page *page, enum node_stat_item item)
 483 {
 484         __inc_node_state(page_pgdat(page), item);
 485 }
 486 EXPORT_SYMBOL(__inc_node_page_state);
 487
 488 void __dec_zone_state(struct zone *zone, enum zone_stat_item item)
 489 {
 490         struct per_cpu_zonestat __percpu *pcp = zone->per_cpu_zonestats;
 491         s8 __percpu *p = pcp->vm_stat_diff + item;
 492         s8 v, t;
 493
 494         /* See __mod_node_page_state */
 495         preempt_disable_nested();
 496
 497         v = __this_cpu_dec_return(*p);
 498         t = __this_cpu_read(pcp->stat_threshold);
 499         if (unlikely(v < - t)) {
 500                 s8 overstep = t >> 1;
 501
 502                 zone_page_state_add(v - overstep, zone, item);
 503                 __this_cpu_write(*p, overstep);
 504         }
 505
 506         preempt_enable_nested();
 507 }
 508
 509 void __dec_node_state(struct pglist_data *pgdat, enum node_stat_item item)
 510 {
 511         struct per_cpu_nodestat __percpu *pcp = pgdat->per_cpu_nodestats;
 512         s8 __percpu *p = pcp->vm_node_stat_diff + item;
 513         s8 v, t;
 514
 515         VM_WARN_ON_ONCE(vmstat_item_in_bytes(item));
 516
 517         /* See __mod_node_page_state */
 518         preempt_disable_nested();
 519
 520         v = __this_cpu_dec_return(*p);
 521         t = __this_cpu_read(pcp->stat_threshold);
 522         if (unlikely(v < - t)) {
 523                 s8 overstep = t >> 1;
 524
 525                 node_page_state_add(v - overstep, pgdat, item);
 526                 __this_cpu_write(*p, overstep);
 527         }
 528
 529         preempt_enable_nested();
 530 }
 531
 532 void __dec_zone_page_state(struct page *page, enum zone_stat_item item)
 533 {
 534         __dec_zone_state(page_zone(page), item);
 535 }
 536 EXPORT_SYMBOL(__dec_zone_page_state);
 537
 538 void __dec_node_page_state(struct page *page, enum node_stat_item item)
 539 {
 540         __dec_node_state(page_pgdat(page), item);
 541 }
 542 EXPORT_SYMBOL(__dec_node_page_state);
 543
 544 #ifdef CONFIG_HAVE_CMPXCHG_LOCAL
 545 /*
 546  * If we have cmpxchg_local support then we do not need to incur the overhead
 547  * that comes with local_irq_save/restore if we use this_cpu_cmpxchg.
 548  *
 549  * mod_state() modifies the zone counter state through atomic per cpu
 550  * operations.
 551  *
 552  * Overstep mode specifies how overstep should handled:
 553  *     0       No overstepping
 554  *     1       Overstepping half of threshold
 555  *     -1      Overstepping minus half of threshold
 556 */
 557 static inline void mod_zone_state(struct zone *zone,
 558        enum zone_stat_item item, long delta, int overstep_mode)
 559 {
 560         struct per_cpu_zonestat __percpu *pcp = zone->per_cpu_zonestats;
 561         s8 __percpu *p = pcp->vm_stat_diff + item;
 562         long o, n, t, z;
 563
 564         do {
 565                 z = 0;  /* overflow to zone counters */
 566
 567                 /*
 568                  * The fetching of the stat_threshold is racy. We may apply
 569                  * a counter threshold to the wrong the cpu if we get
 570                  * rescheduled while executing here. However, the next
 571                  * counter update will apply the threshold again and
 572                  * therefore bring the counter under the threshold again.
 573                  *
 574                  * Most of the time the thresholds are the same anyways
 575                  * for all cpus in a zone.
 576                  */
 577                 t = this_cpu_read(pcp->stat_threshold);
 578
 579                 o = this_cpu_read(*p);
 580                 n = delta + o;
 581
 582                 if (abs(n) > t) {
 583                         int os = overstep_mode * (t >> 1) ;
 584
 585                         /* Overflow must be added to zone counters */
 586                         z = n + os;
 587                         n = -os;
 588                 }
 589         } while (this_cpu_cmpxchg(*p, o, n) != o);
 590
 591         if (z)
 592                 zone_page_state_add(z, zone, item);
 593 }
 594
 595 void mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
 596                          long delta)
 597 {
 598         mod_zone_state(zone, item, delta, 0);
 599 }
 600 EXPORT_SYMBOL(mod_zone_page_state);
 601
 602 void inc_zone_page_state(struct page *page, enum zone_stat_item item)
 603 {
 604         mod_zone_state(page_zone(page), item, 1, 1);
 605 }
 606 EXPORT_SYMBOL(inc_zone_page_state);
 607
 608 void dec_zone_page_state(struct page *page, enum zone_stat_item item)
 609 {
 610         mod_zone_state(page_zone(page), item, -1, -1);
 611 }
 612 EXPORT_SYMBOL(dec_zone_page_state);
 613
 614 static inline void mod_node_state(struct pglist_data *pgdat,
 615        enum node_stat_item item, int delta, int overstep_mode)
 616 {
 617         struct per_cpu_nodestat __percpu *pcp = pgdat->per_cpu_nodestats;
 618         s8 __percpu *p = pcp->vm_node_stat_diff + item;
 619         long o, n, t, z;
 620
 621         if (vmstat_item_in_bytes(item)) {
 622                 /*
 623                  * Only cgroups use subpage accounting right now; at
 624                  * the global level, these items still change in
 625                  * multiples of whole pages. Store them as pages
 626                  * internally to keep the per-cpu counters compact.
 627                  */
 628                 VM_WARN_ON_ONCE(delta & (PAGE_SIZE - 1));
 629                 delta >>= PAGE_SHIFT;
 630         }
 631
 632         do {
 633                 z = 0;  /* overflow to node counters */
 634
 635                 /*
 636                  * The fetching of the stat_threshold is racy. We may apply
 637                  * a counter threshold to the wrong the cpu if we get
 638                  * rescheduled while executing here. However, the next
 639                  * counter update will apply the threshold again and
 640                  * therefore bring the counter under the threshold again.
 641                  *
 642                  * Most of the time the thresholds are the same anyways
 643                  * for all cpus in a node.
 644                  */
 645                 t = this_cpu_read(pcp->stat_threshold);
 646
 647                 o = this_cpu_read(*p);
 648                 n = delta + o;
 649
 650                 if (abs(n) > t) {
 651                         int os = overstep_mode * (t >> 1) ;
 652
 653                         /* Overflow must be added to node counters */
 654                         z = n + os;
 655                         n = -os;
 656                 }
 657         } while (this_cpu_cmpxchg(*p, o, n) != o);
 658
 659         if (z)
 660                 node_page_state_add(z, pgdat, item);
 661 }
 662
 663 void mod_node_page_state(struct pglist_data *pgdat, enum node_stat_item item,
 664                                         long delta)
 665 {
 666         mod_node_state(pgdat, item, delta, 0);
 667 }
 668 EXPORT_SYMBOL(mod_node_page_state);
 669
 670 void inc_node_state(struct pglist_data *pgdat, enum node_stat_item item)
 671 {
 672         mod_node_state(pgdat, item, 1, 1);
 673 }
 674
 675 void inc_node_page_state(struct page *page, enum node_stat_item item)
 676 {
 677         mod_node_state(page_pgdat(page), item, 1, 1);
 678 }
 679 EXPORT_SYMBOL(inc_node_page_state);
 680
 681 void dec_node_page_state(struct page *page, enum node_stat_item item)
 682 {
 683         mod_node_state(page_pgdat(page), item, -1, -1);
 684 }
 685 EXPORT_SYMBOL(dec_node_page_state);
 686 #else
 687 /*
 688  * Use interrupt disable to serialize counter updates
 689  */
 690 void mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
 691                          long delta)
 692 {
 693         unsigned long flags;
 694
 695         local_irq_save(flags);
 696         __mod_zone_page_state(zone, item, delta);
 697         local_irq_restore(flags);
 698 }
 699 EXPORT_SYMBOL(mod_zone_page_state);
 700
 701 void inc_zone_page_state(struct page *page, enum zone_stat_item item)
 702 {
 703         unsigned long flags;
 704         struct zone *zone;
 705
 706         zone = page_zone(page);
 707         local_irq_save(flags);
 708         __inc_zone_state(zone, item);
 709         local_irq_restore(flags);
 710 }
 711 EXPORT_SYMBOL(inc_zone_page_state);
 712
 713 void dec_zone_page_state(struct page *page, enum zone_stat_item item)
 714 {
 715         unsigned long flags;
 716
 717         local_irq_save(flags);
 718         __dec_zone_page_state(page, item);
 719         local_irq_restore(flags);
 720 }
 721 EXPORT_SYMBOL(dec_zone_page_state);
 722
 723 void inc_node_state(struct pglist_data *pgdat, enum node_stat_item item)
 724 {
 725         unsigned long flags;
 726
 727         local_irq_save(flags);
 728         __inc_node_state(pgdat, item);
 729         local_irq_restore(flags);
 730 }
 731 EXPORT_SYMBOL(inc_node_state);
 732
 733 void mod_node_page_state(struct pglist_data *pgdat, enum node_stat_item item,
 734                                         long delta)
 735 {
 736         unsigned long flags;
 737
 738         local_irq_save(flags);
 739         __mod_node_page_state(pgdat, item, delta);
 740         local_irq_restore(flags);
 741 }
 742 EXPORT_SYMBOL(mod_node_page_state);
 743
 744 void inc_node_page_state(struct page *page, enum node_stat_item item)
 745 {
 746         unsigned long flags;
 747         struct pglist_data *pgdat;
 748
 749         pgdat = page_pgdat(page);
 750         local_irq_save(flags);
 751         __inc_node_state(pgdat, item);
 752         local_irq_restore(flags);
 753 }
 754 EXPORT_SYMBOL(inc_node_page_state);
 755
 756 void dec_node_page_state(struct page *page, enum node_stat_item item)
 757 {
 758         unsigned long flags;
 759
 760         local_irq_save(flags);
 761         __dec_node_page_state(page, item);
 762         local_irq_restore(flags);
 763 }
 764 EXPORT_SYMBOL(dec_node_page_state);
 765 #endif
 766
 767 /*
 768  * Fold a differential into the global counters.
 769  * Returns the number of counters updated.
 770  */
 771 static int fold_diff(int *zone_diff, int *node_diff)
 772 {
 773         int i;
 774         int changes = 0;
 775
 776         for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
 777                 if (zone_diff[i]) {
 778                         atomic_long_add(zone_diff[i], &vm_zone_stat[i]);
 779                         changes++;
 780         }
 781
 782         for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++)
 783                 if (node_diff[i]) {
 784                         atomic_long_add(node_diff[i], &vm_node_stat[i]);
 785                         changes++;
 786         }
 787         return changes;
 788 }
 789
 790 /*
 791  * Update the zone counters for the current cpu.
 792  *
 793  * Note that refresh_cpu_vm_stats strives to only access
 794  * node local memory. The per cpu pagesets on remote zones are placed
 795  * in the memory local to the processor using that pageset. So the
 796  * loop over all zones will access a series of cachelines local to
 797  * the processor.
 798  *
 799  * The call to zone_page_state_add updates the cachelines with the
 800  * statistics in the remote zone struct as well as the global cachelines
 801  * with the global counters. These could cause remote node cache line
 802  * bouncing and will have to be only done when necessary.
 803  *
 804  * The function returns the number of global counters updated.
 805  */
 806 static int refresh_cpu_vm_stats(bool do_pagesets)
 807 {
 808         struct pglist_data *pgdat;
 809         struct zone *zone;
 810         int i;
 811         int global_zone_diff[NR_VM_ZONE_STAT_ITEMS] = { 0, };
 812         int global_node_diff[NR_VM_NODE_STAT_ITEMS] = { 0, };
 813         int changes = 0;
 814
 815         for_each_populated_zone(zone) {
 816                 struct per_cpu_zonestat __percpu *pzstats = zone->per_cpu_zonestats;
 817 #ifdef CONFIG_NUMA
 818                 struct per_cpu_pages __percpu *pcp = zone->per_cpu_pageset;
 819 #endif
 820
 821                 for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++) {
 822                         int v;
 823
 824                         v = this_cpu_xchg(pzstats->vm_stat_diff[i], 0);
 825                         if (v) {
 826
 827                                 atomic_long_add(v, &zone->vm_stat[i]);
 828                                 global_zone_diff[i] += v;
 829 #ifdef CONFIG_NUMA
 830                                 /* 3 seconds idle till flush */
 831                                 __this_cpu_write(pcp->expire, 3);
 832 #endif
 833                         }
 834                 }
 835 #ifdef CONFIG_NUMA
 836
 837                 if (do_pagesets) {
 838                         cond_resched();
 839                         /*
 840                          * Deal with draining the remote pageset of this
 841                          * processor
 842                          *
 843                          * Check if there are pages remaining in this pageset
 844                          * if not then there is nothing to expire.
 845                          */
 846                         if (!__this_cpu_read(pcp->expire) ||
 847                                !__this_cpu_read(pcp->count))
 848                                 continue;
 849
 850                         /*
 851                          * We never drain zones local to this processor.
 852                          */
 853                         if (zone_to_nid(zone) == numa_node_id()) {
 854                                 __this_cpu_write(pcp->expire, 0);
 855                                 continue;
 856                         }
 857
 858                         if (__this_cpu_dec_return(pcp->expire))
 859                                 continue;
 860
 861                         if (__this_cpu_read(pcp->count)) {
 862                                 drain_zone_pages(zone, this_cpu_ptr(pcp));
 863                                 changes++;
 864                         }
 865                 }
 866 #endif
 867         }
 868
 869         for_each_online_pgdat(pgdat) {
 870                 struct per_cpu_nodestat __percpu *p = pgdat->per_cpu_nodestats;
 871
 872                 for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++) {
 873                         int v;
 874
 875                         v = this_cpu_xchg(p->vm_node_stat_diff[i], 0);
 876                         if (v) {
 877                                 atomic_long_add(v, &pgdat->vm_stat[i]);
 878                                 global_node_diff[i] += v;
 879                         }
 880                 }
 881         }
 882
 883         changes += fold_diff(global_zone_diff, global_node_diff);
 884         return changes;
 885 }
 886
 887 /*
 888  * Fold the data for an offline cpu into the global array.
 889  * There cannot be any access by the offline cpu and therefore
 890  * synchronization is simplified.
 891  */
 892 void cpu_vm_stats_fold(int cpu)
 893 {
 894         struct pglist_data *pgdat;
 895         struct zone *zone;
 896         int i;
 897         int global_zone_diff[NR_VM_ZONE_STAT_ITEMS] = { 0, };
 898         int global_node_diff[NR_VM_NODE_STAT_ITEMS] = { 0, };
 899
 900         for_each_populated_zone(zone) {
 901                 struct per_cpu_zonestat *pzstats;
 902
 903                 pzstats = per_cpu_ptr(zone->per_cpu_zonestats, cpu);
 904
 905                 for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++) {
 906                         if (pzstats->vm_stat_diff[i]) {
 907                                 int v;
 908
 909                                 v = pzstats->vm_stat_diff[i];
 910                                 pzstats->vm_stat_diff[i] = 0;
 911                                 atomic_long_add(v, &zone->vm_stat[i]);
 912                                 global_zone_diff[i] += v;
 913                         }
 914                 }
 915 #ifdef CONFIG_NUMA
 916                 for (i = 0; i < NR_VM_NUMA_EVENT_ITEMS; i++) {
 917                         if (pzstats->vm_numa_event[i]) {
 918                                 unsigned long v;
 919
 920                                 v = pzstats->vm_numa_event[i];
 921                                 pzstats->vm_numa_event[i] = 0;
 922                                 zone_numa_event_add(v, zone, i);
 923                         }
 924                 }
 925 #endif
 926         }
 927
 928         for_each_online_pgdat(pgdat) {
 929                 struct per_cpu_nodestat *p;
 930
 931                 p = per_cpu_ptr(pgdat->per_cpu_nodestats, cpu);
 932
 933                 for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++)
 934                         if (p->vm_node_stat_diff[i]) {
 935                                 int v;
 936
 937                                 v = p->vm_node_stat_diff[i];
 938                                 p->vm_node_stat_diff[i] = 0;
 939                                 atomic_long_add(v, &pgdat->vm_stat[i]);
 940                                 global_node_diff[i] += v;
 941                         }
 942         }
 943
 944         fold_diff(global_zone_diff, global_node_diff);
 945 }
 946
 947 /*
 948  * this is only called if !populated_zone(zone), which implies no other users of
 949  * pset->vm_stat_diff[] exist.
 950  */
 951 void drain_zonestat(struct zone *zone, struct per_cpu_zonestat *pzstats)
 952 {
 953         unsigned long v;
 954         int i;
 955
 956         for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++) {
 957                 if (pzstats->vm_stat_diff[i]) {
 958                         v = pzstats->vm_stat_diff[i];
 959                         pzstats->vm_stat_diff[i] = 0;
 960                         zone_page_state_add(v, zone, i);
 961                 }
 962         }
 963
 964 #ifdef CONFIG_NUMA
 965         for (i = 0; i < NR_VM_NUMA_EVENT_ITEMS; i++) {
 966                 if (pzstats->vm_numa_event[i]) {
 967                         v = pzstats->vm_numa_event[i];
 968                         pzstats->vm_numa_event[i] = 0;
 969                         zone_numa_event_add(v, zone, i);
 970                 }
 971         }
 972 #endif
 973 }
 974 #endif
 975
 976 #ifdef CONFIG_NUMA
 977 /*
 978  * Determine the per node value of a stat item. This function
 979  * is called frequently in a NUMA machine, so try to be as
 980  * frugal as possible.
 981  */
 982 unsigned long sum_zone_node_page_state(int node,
 983                                  enum zone_stat_item item)
 984 {
 985         struct zone *zones = NODE_DATA(node)->node_zones;
 986         int i;
 987         unsigned long count = 0;
 988
 989         for (i = 0; i < MAX_NR_ZONES; i++)
 990                 count += zone_page_state(zones + i, item);
 991
 992         return count;
 993 }
 994
 995 /* Determine the per node value of a numa stat item. */
 996 unsigned long sum_zone_numa_event_state(int node,
 997                                  enum numa_stat_item item)
 998 {
 999         struct zone *zones = NODE_DATA(node)->node_zones;
1000         unsigned long count = 0;
1001         int i;
1002
1003         for (i = 0; i < MAX_NR_ZONES; i++)
1004                 count += zone_numa_event_state(zones + i, item);
1005
1006         return count;
1007 }
1008
1009 /*
1010  * Determine the per node value of a stat item.
1011  */
1012 unsigned long node_page_state_pages(struct pglist_data *pgdat,
1013                                     enum node_stat_item item)
1014 {
1015         long x = atomic_long_read(&pgdat->vm_stat[item]);
1016 #ifdef CONFIG_SMP
1017         if (x < 0)
1018                 x = 0;
1019 #endif
1020         return x;
1021 }
1022
1023 unsigned long node_page_state(struct pglist_data *pgdat,
1024                               enum node_stat_item item)
1025 {
1026         VM_WARN_ON_ONCE(vmstat_item_in_bytes(item));
1027
1028         return node_page_state_pages(pgdat, item);
1029 }
1030 #endif
1031
1032 #ifdef CONFIG_COMPACTION
1033
1034 struct contig_page_info {
1035         unsigned long free_pages;
1036         unsigned long free_blocks_total;
1037         unsigned long free_blocks_suitable;
1038 };
1039
1040 /*
1041  * Calculate the number of free pages in a zone, how many contiguous
1042  * pages are free and how many are large enough to satisfy an allocation of
1043  * the target size. Note that this function makes no attempt to estimate
1044  * how many suitable free blocks there *might* be if MOVABLE pages were
1045  * migrated. Calculating that is possible, but expensive and can be
1046  * figured out from userspace
1047  */
1048 static void fill_contig_page_info(struct zone *zone,
1049                                 unsigned int suitable_order,
1050                                 struct contig_page_info *info)
1051 {
1052         unsigned int order;
1053
1054         info->free_pages = 0;
1055         info->free_blocks_total = 0;
1056         info->free_blocks_suitable = 0;
1057
1058         for (order = 0; order <= MAX_ORDER; order++) {
1059                 unsigned long blocks;
1060
1061                 /*
1062                  * Count number of free blocks.
1063                  *
1064                  * Access to nr_free is lockless as nr_free is used only for
1065                  * diagnostic purposes. Use data_race to avoid KCSAN warning.
1066                  */
1067                 blocks = data_race(zone->free_area[order].nr_free);
1068                 info->free_blocks_total += blocks;
1069
1070                 /* Count free base pages */
1071                 info->free_pages += blocks << order;
1072
1073                 /* Count the suitable free blocks */
1074                 if (order >= suitable_order)
1075                         info->free_blocks_suitable += blocks <<
1076                                                 (order - suitable_order);
1077         }
1078 }
1079
1080 /*
1081  * A fragmentation index only makes sense if an allocation of a requested
1082  * size would fail. If that is true, the fragmentation index indicates
1083  * whether external fragmentation or a lack of memory was the problem.
1084  * The value can be used to determine if page reclaim or compaction
1085  * should be used
1086  */
1087 static int __fragmentation_index(unsigned int order, struct contig_page_info *info)
1088 {
1089         unsigned long requested = 1UL << order;
1090
1091         if (WARN_ON_ONCE(order > MAX_ORDER))
1092                 return 0;
1093
1094         if (!info->free_blocks_total)
1095                 return 0;
1096
1097         /* Fragmentation index only makes sense when a request would fail */
1098         if (info->free_blocks_suitable)
1099                 return -1000;
1100
1101         /*
1102          * Index is between 0 and 1 so return within 3 decimal places
1103          *
1104          * 0 => allocation would fail due to lack of memory
1105          * 1 => allocation would fail due to fragmentation
1106          */
1107         return 1000 - div_u64( (1000+(div_u64(info->free_pages * 1000ULL, requested))), info->free_blocks_total);
1108 }
1109
1110 /*
1111  * Calculates external fragmentation within a zone wrt the given order.
1112  * It is defined as the percentage of pages found in blocks of size
1113  * less than 1 << order. It returns values in range [0, 100].
1114  */
1115 unsigned int extfrag_for_order(struct zone *zone, unsigned int order)
1116 {
1117         struct contig_page_info info;
1118
1119         fill_contig_page_info(zone, order, &info);
1120         if (info.free_pages == 0)
1121                 return 0;
1122
1123         return div_u64((info.free_pages -
1124                         (info.free_blocks_suitable << order)) * 100,
1125                         info.free_pages);
1126 }
1127
1128 /* Same as __fragmentation index but allocs contig_page_info on stack */
1129 int fragmentation_index(struct zone *zone, unsigned int order)
1130 {
1131         struct contig_page_info info;
1132
1133         fill_contig_page_info(zone, order, &info);
1134         return __fragmentation_index(order, &info);
1135 }
1136 #endif
1137
1138 #if defined(CONFIG_PROC_FS) || defined(CONFIG_SYSFS) || \
1139     defined(CONFIG_NUMA) || defined(CONFIG_MEMCG)
1140 #ifdef CONFIG_ZONE_DMA
1141 #define TEXT_FOR_DMA(xx) xx "_dma",
1142 #else
1143 #define TEXT_FOR_DMA(xx)
1144 #endif
1145
1146 #ifdef CONFIG_ZONE_DMA32
1147 #define TEXT_FOR_DMA32(xx) xx "_dma32",
1148 #else
1149 #define TEXT_FOR_DMA32(xx)
1150 #endif
1151
1152 #ifdef CONFIG_HIGHMEM
1153 #define TEXT_FOR_HIGHMEM(xx) xx "_high",
1154 #else
1155 #define TEXT_FOR_HIGHMEM(xx)
1156 #endif
1157
1158 #ifdef CONFIG_ZONE_DEVICE
1159 #define TEXT_FOR_DEVICE(xx) xx "_device",
1160 #else
1161 #define TEXT_FOR_DEVICE(xx)
1162 #endif
1163
1164 #define TEXTS_FOR_ZONES(xx) TEXT_FOR_DMA(xx) TEXT_FOR_DMA32(xx) xx "_normal", \
1165                                         TEXT_FOR_HIGHMEM(xx) xx "_movable", \
1166                                         TEXT_FOR_DEVICE(xx)
1167
1168 const char * const vmstat_text[] = {
1169         /* enum zone_stat_item counters */
1170         "nr_free_pages",
1171         "nr_zone_inactive_anon",
1172         "nr_zone_active_anon",
1173         "nr_zone_inactive_file",
1174         "nr_zone_active_file",
1175         "nr_zone_unevictable",
1176         "nr_zone_write_pending",
1177         "nr_mlock",
1178         "nr_bounce",
1179 #if IS_ENABLED(CONFIG_ZSMALLOC)
1180         "nr_zspages",
1181 #endif
1182         "nr_free_cma",
1183 #ifdef CONFIG_UNACCEPTED_MEMORY
1184         "nr_unaccepted",
1185 #endif
1186
1187         /* enum numa_stat_item counters */
1188 #ifdef CONFIG_NUMA
1189         "numa_hit",
1190         "numa_miss",
1191         "numa_foreign",
1192         "numa_interleave",
1193         "numa_local",
1194         "numa_other",
1195 #endif
1196
1197         /* enum node_stat_item counters */
1198         "nr_inactive_anon",
1199         "nr_active_anon",
1200         "nr_inactive_file",
1201         "nr_active_file",
1202         "nr_unevictable",
1203         "nr_slab_reclaimable",
1204         "nr_slab_unreclaimable",
1205         "nr_isolated_anon",
1206         "nr_isolated_file",
1207         "workingset_nodes",
1208         "workingset_refault_anon",
1209         "workingset_refault_file",
1210         "workingset_activate_anon",
1211         "workingset_activate_file",
1212         "workingset_restore_anon",
1213         "workingset_restore_file",
1214         "workingset_nodereclaim",
1215         "nr_anon_pages",
1216         "nr_mapped",
1217         "nr_file_pages",
1218         "nr_dirty",
1219         "nr_writeback",
1220         "nr_writeback_temp",
1221         "nr_shmem",
1222         "nr_shmem_hugepages",
1223         "nr_shmem_pmdmapped",
1224         "nr_file_hugepages",
1225         "nr_file_pmdmapped",
1226         "nr_anon_transparent_hugepages",
1227         "nr_vmscan_write",
1228         "nr_vmscan_immediate_reclaim",
1229         "nr_dirtied",
1230         "nr_written",
1231         "nr_throttled_written",
1232         "nr_kernel_misc_reclaimable",
1233         "nr_foll_pin_acquired",
1234         "nr_foll_pin_released",
1235         "nr_kernel_stack",
1236 #if IS_ENABLED(CONFIG_SHADOW_CALL_STACK)
1237         "nr_shadow_call_stack",
1238 #endif
1239         "nr_page_table_pages",
1240         "nr_sec_page_table_pages",
1241 #ifdef CONFIG_SWAP
1242         "nr_swapcached",
1243 #endif
1244 #ifdef CONFIG_NUMA_BALANCING
1245         "pgpromote_success",
1246         "pgpromote_candidate",
1247 #endif
1248
1249         /* enum writeback_stat_item counters */
1250         "nr_dirty_threshold",
1251         "nr_dirty_background_threshold",
1252
1253 #if defined(CONFIG_VM_EVENT_COUNTERS) || defined(CONFIG_MEMCG)
1254         /* enum vm_event_item counters */
1255         "pgpgin",
1256         "pgpgout",
1257         "pswpin",
1258         "pswpout",
1259
1260         TEXTS_FOR_ZONES("pgalloc")
1261         TEXTS_FOR_ZONES("allocstall")
1262         TEXTS_FOR_ZONES("pgskip")
1263
1264         "pgfree",
1265         "pgactivate",
1266         "pgdeactivate",
1267         "pglazyfree",
1268
1269         "pgfault",
1270         "pgmajfault",
1271         "pglazyfreed",
1272
1273         "pgrefill",
1274         "pgreuse",
1275         "pgsteal_kswapd",
1276         "pgsteal_direct",
1277         "pgsteal_khugepaged",
1278         "pgdemote_kswapd",
1279         "pgdemote_direct",
1280         "pgdemote_khugepaged",
1281         "pgscan_kswapd",
1282         "pgscan_direct",
1283         "pgscan_khugepaged",
1284         "pgscan_direct_throttle",
1285         "pgscan_anon",
1286         "pgscan_file",
1287         "pgsteal_anon",
1288         "pgsteal_file",
1289
1290 #ifdef CONFIG_NUMA
1291         "zone_reclaim_failed",
1292 #endif
1293         "pginodesteal",
1294         "slabs_scanned",
1295         "kswapd_inodesteal",
1296         "kswapd_low_wmark_hit_quickly",
1297         "kswapd_high_wmark_hit_quickly",
1298         "pageoutrun",
1299
1300         "pgrotated",
1301
1302         "drop_pagecache",
1303         "drop_slab",
1304         "oom_kill",
1305
1306 #ifdef CONFIG_NUMA_BALANCING
1307         "numa_pte_updates",
1308         "numa_huge_pte_updates",
1309         "numa_hint_faults",
1310         "numa_hint_faults_local",
1311         "numa_pages_migrated",
1312 #endif
1313 #ifdef CONFIG_MIGRATION
1314         "pgmigrate_success",
1315         "pgmigrate_fail",
1316         "thp_migration_success",
1317         "thp_migration_fail",
1318         "thp_migration_split",
1319 #endif
1320 #ifdef CONFIG_COMPACTION
1321         "compact_migrate_scanned",
1322         "compact_free_scanned",
1323         "compact_isolated",
1324         "compact_stall",
1325         "compact_fail",
1326         "compact_success",
1327         "compact_daemon_wake",
1328         "compact_daemon_migrate_scanned",
1329         "compact_daemon_free_scanned",
1330 #endif
1331
1332 #ifdef CONFIG_HUGETLB_PAGE
1333         "htlb_buddy_alloc_success",
1334         "htlb_buddy_alloc_fail",
1335 #endif
1336 #ifdef CONFIG_CMA
1337         "cma_alloc_success",
1338         "cma_alloc_fail",
1339 #endif
1340         "unevictable_pgs_culled",
1341         "unevictable_pgs_scanned",
1342         "unevictable_pgs_rescued",
1343         "unevictable_pgs_mlocked",
1344         "unevictable_pgs_munlocked",
1345         "unevictable_pgs_cleared",
1346         "unevictable_pgs_stranded",
1347
1348 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
1349         "thp_fault_alloc",
1350         "thp_fault_fallback",
1351         "thp_fault_fallback_charge",
1352         "thp_collapse_alloc",
1353         "thp_collapse_alloc_failed",
1354         "thp_file_alloc",
1355         "thp_file_fallback",
1356         "thp_file_fallback_charge",
1357         "thp_file_mapped",
1358         "thp_split_page",
1359         "thp_split_page_failed",
1360         "thp_deferred_split_page",
1361         "thp_split_pmd",
1362         "thp_scan_exceed_none_pte",
1363         "thp_scan_exceed_swap_pte",
1364         "thp_scan_exceed_share_pte",
1365 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1366         "thp_split_pud",
1367 #endif
1368         "thp_zero_page_alloc",
1369         "thp_zero_page_alloc_failed",
1370         "thp_swpout",
1371         "thp_swpout_fallback",
1372 #endif
1373 #ifdef CONFIG_MEMORY_BALLOON
1374         "balloon_inflate",
1375         "balloon_deflate",
1376 #ifdef CONFIG_BALLOON_COMPACTION
1377         "balloon_migrate",
1378 #endif
1379 #endif /* CONFIG_MEMORY_BALLOON */
1380 #ifdef CONFIG_DEBUG_TLBFLUSH
1381         "nr_tlb_remote_flush",
1382         "nr_tlb_remote_flush_received",
1383         "nr_tlb_local_flush_all",
1384         "nr_tlb_local_flush_one",
1385 #endif /* CONFIG_DEBUG_TLBFLUSH */
1386
1387 #ifdef CONFIG_SWAP
1388         "swap_ra",
1389         "swap_ra_hit",
1390 #ifdef CONFIG_KSM
1391         "ksm_swpin_copy",
1392 #endif
1393 #endif
1394 #ifdef CONFIG_KSM
1395         "cow_ksm",
1396 #endif
1397 #ifdef CONFIG_ZSWAP
1398         "zswpin",
1399         "zswpout",
1400 #endif
1401 #ifdef CONFIG_X86
1402         "direct_map_level2_splits",
1403         "direct_map_level3_splits",
1404 #endif
1405 #ifdef CONFIG_PER_VMA_LOCK_STATS
1406         "vma_lock_success",
1407         "vma_lock_abort",
1408         "vma_lock_retry",
1409         "vma_lock_miss",
1410 #endif
1411 #endif /* CONFIG_VM_EVENT_COUNTERS || CONFIG_MEMCG */
1412 };
1413 #endif /* CONFIG_PROC_FS || CONFIG_SYSFS || CONFIG_NUMA || CONFIG_MEMCG */
1414
1415 #if (defined(CONFIG_DEBUG_FS) && defined(CONFIG_COMPACTION)) || \
1416      defined(CONFIG_PROC_FS)
1417 static void *frag_start(struct seq_file *m, loff_t *pos)
1418 {
1419         pg_data_t *pgdat;
1420         loff_t node = *pos;
1421
1422         for (pgdat = first_online_pgdat();
1423              pgdat && node;
1424              pgdat = next_online_pgdat(pgdat))
1425                 --node;
1426
1427         return pgdat;
1428 }
1429
1430 static void *frag_next(struct seq_file *m, void *arg, loff_t *pos)
1431 {
1432         pg_data_t *pgdat = (pg_data_t *)arg;
1433
1434         (*pos)++;
1435         return next_online_pgdat(pgdat);
1436 }
1437
1438 static void frag_stop(struct seq_file *m, void *arg)
1439 {
1440 }
1441
1442 /*
1443  * Walk zones in a node and print using a callback.
1444  * If @assert_populated is true, only use callback for zones that are populated.
1445  */
1446 static void walk_zones_in_node(struct seq_file *m, pg_data_t *pgdat,
1447                 bool assert_populated, bool nolock,
1448                 void (*print)(struct seq_file *m, pg_data_t *, struct zone *))
1449 {
1450         struct zone *zone;
1451         struct zone *node_zones = pgdat->node_zones;
1452         unsigned long flags;
1453
1454         for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
1455                 if (assert_populated && !populated_zone(zone))
1456                         continue;
1457
1458                 if (!nolock)
1459                         spin_lock_irqsave(&zone->lock, flags);
1460                 print(m, pgdat, zone);
1461                 if (!nolock)
1462                         spin_unlock_irqrestore(&zone->lock, flags);
1463         }
1464 }
1465 #endif
1466
1467 #ifdef CONFIG_PROC_FS
1468 static void frag_show_print(struct seq_file *m, pg_data_t *pgdat,
1469                                                 struct zone *zone)
1470 {
1471         int order;
1472
1473         seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
1474         for (order = 0; order <= MAX_ORDER; ++order)
1475                 /*
1476                  * Access to nr_free is lockless as nr_free is used only for
1477                  * printing purposes. Use data_race to avoid KCSAN warning.
1478                  */
1479                 seq_printf(m, "%6lu ", data_race(zone->free_area[order].nr_free));
1480         seq_putc(m, '\n');
1481 }
1482
1483 /*
1484  * This walks the free areas for each zone.
1485  */
1486 static int frag_show(struct seq_file *m, void *arg)
1487 {
1488         pg_data_t *pgdat = (pg_data_t *)arg;
1489         walk_zones_in_node(m, pgdat, true, false, frag_show_print);
1490         return 0;
1491 }
1492
1493 static void pagetypeinfo_showfree_print(struct seq_file *m,
1494                                         pg_data_t *pgdat, struct zone *zone)
1495 {
1496         int order, mtype;
1497
1498         for (mtype = 0; mtype < MIGRATE_TYPES; mtype++) {
1499                 seq_printf(m, "Node %4d, zone %8s, type %12s ",
1500                                         pgdat->node_id,
1501                                         zone->name,
1502                                         migratetype_names[mtype]);
1503                 for (order = 0; order <= MAX_ORDER; ++order) {
1504                         unsigned long freecount = 0;
1505                         struct free_area *area;
1506                         struct list_head *curr;
1507                         bool overflow = false;
1508
1509                         area = &(zone->free_area[order]);
1510
1511                         list_for_each(curr, &area->free_list[mtype]) {
1512                                 /*
1513                                  * Cap the free_list iteration because it might
1514                                  * be really large and we are under a spinlock
1515                                  * so a long time spent here could trigger a
1516                                  * hard lockup detector. Anyway this is a
1517                                  * debugging tool so knowing there is a handful
1518                                  * of pages of this order should be more than
1519                                  * sufficient.
1520                                  */
1521                                 if (++freecount >= 100000) {
1522                                         overflow = true;
1523                                         break;
1524                                 }
1525                         }
1526                         seq_printf(m, "%s%6lu ", overflow ? ">" : "", freecount);
1527                         spin_unlock_irq(&zone->lock);
1528                         cond_resched();
1529                         spin_lock_irq(&zone->lock);
1530                 }
1531                 seq_putc(m, '\n');
1532         }
1533 }
1534
1535 /* Print out the free pages at each order for each migatetype */
1536 static void pagetypeinfo_showfree(struct seq_file *m, void *arg)
1537 {
1538         int order;
1539         pg_data_t *pgdat = (pg_data_t *)arg;
1540
1541         /* Print header */
1542         seq_printf(m, "%-43s ", "Free pages count per migrate type at order");
1543         for (order = 0; order <= MAX_ORDER; ++order)
1544                 seq_printf(m, "%6d ", order);
1545         seq_putc(m, '\n');
1546
1547         walk_zones_in_node(m, pgdat, true, false, pagetypeinfo_showfree_print);
1548 }
1549
1550 static void pagetypeinfo_showblockcount_print(struct seq_file *m,
1551                                         pg_data_t *pgdat, struct zone *zone)
1552 {
1553         int mtype;
1554         unsigned long pfn;
1555         unsigned long start_pfn = zone->zone_start_pfn;
1556         unsigned long end_pfn = zone_end_pfn(zone);
1557         unsigned long count[MIGRATE_TYPES] = { 0, };
1558
1559         for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
1560                 struct page *page;
1561
1562                 page = pfn_to_online_page(pfn);
1563                 if (!page)
1564                         continue;
1565
1566                 if (page_zone(page) != zone)
1567                         continue;
1568
1569                 mtype = get_pageblock_migratetype(page);
1570
1571                 if (mtype < MIGRATE_TYPES)
1572                         count[mtype]++;
1573         }
1574
1575         /* Print counts */
1576         seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
1577         for (mtype = 0; mtype < MIGRATE_TYPES; mtype++)
1578                 seq_printf(m, "%12lu ", count[mtype]);
1579         seq_putc(m, '\n');
1580 }
1581
1582 /* Print out the number of pageblocks for each migratetype */
1583 static void pagetypeinfo_showblockcount(struct seq_file *m, void *arg)
1584 {
1585         int mtype;
1586         pg_data_t *pgdat = (pg_data_t *)arg;
1587
1588         seq_printf(m, "\n%-23s", "Number of blocks type ");
1589         for (mtype = 0; mtype < MIGRATE_TYPES; mtype++)
1590                 seq_printf(m, "%12s ", migratetype_names[mtype]);
1591         seq_putc(m, '\n');
1592         walk_zones_in_node(m, pgdat, true, false,
1593                 pagetypeinfo_showblockcount_print);
1594 }
1595
1596 /*
1597  * Print out the number of pageblocks for each migratetype that contain pages
1598  * of other types. This gives an indication of how well fallbacks are being
1599  * contained by rmqueue_fallback(). It requires information from PAGE_OWNER
1600  * to determine what is going on
1601  */
1602 static void pagetypeinfo_showmixedcount(struct seq_file *m, pg_data_t *pgdat)
1603 {
1604 #ifdef CONFIG_PAGE_OWNER
1605         int mtype;
1606
1607         if (!static_branch_unlikely(&page_owner_inited))
1608                 return;
1609
1610         drain_all_pages(NULL);
1611
1612         seq_printf(m, "\n%-23s", "Number of mixed blocks ");
1613         for (mtype = 0; mtype < MIGRATE_TYPES; mtype++)
1614                 seq_printf(m, "%12s ", migratetype_names[mtype]);
1615         seq_putc(m, '\n');
1616
1617         walk_zones_in_node(m, pgdat, true, true,
1618                 pagetypeinfo_showmixedcount_print);
1619 #endif /* CONFIG_PAGE_OWNER */
1620 }
1621
1622 /*
1623  * This prints out statistics in relation to grouping pages by mobility.
1624  * It is expensive to collect so do not constantly read the file.
1625  */
1626 static int pagetypeinfo_show(struct seq_file *m, void *arg)
1627 {
1628         pg_data_t *pgdat = (pg_data_t *)arg;
1629
1630         /* check memoryless node */
1631         if (!node_state(pgdat->node_id, N_MEMORY))
1632                 return 0;
1633
1634         seq_printf(m, "Page block order: %d\n", pageblock_order);
1635         seq_printf(m, "Pages per block:  %lu\n", pageblock_nr_pages);
1636         seq_putc(m, '\n');
1637         pagetypeinfo_showfree(m, pgdat);
1638         pagetypeinfo_showblockcount(m, pgdat);
1639         pagetypeinfo_showmixedcount(m, pgdat);
1640
1641         return 0;
1642 }
1643
1644 static const struct seq_operations fragmentation_op = {
1645         .start  = frag_start,
1646         .next   = frag_next,
1647         .stop   = frag_stop,
1648         .show   = frag_show,
1649 };
1650
1651 static const struct seq_operations pagetypeinfo_op = {
1652         .start  = frag_start,
1653         .next   = frag_next,
1654         .stop   = frag_stop,
1655         .show   = pagetypeinfo_show,
1656 };
1657
1658 static bool is_zone_first_populated(pg_data_t *pgdat, struct zone *zone)
1659 {
1660         int zid;
1661
1662         for (zid = 0; zid < MAX_NR_ZONES; zid++) {
1663                 struct zone *compare = &pgdat->node_zones[zid];
1664
1665                 if (populated_zone(compare))
1666                         return zone == compare;
1667         }
1668
1669         return false;
1670 }
1671
1672 static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
1673                                                         struct zone *zone)
1674 {
1675         int i;
1676         seq_printf(m, "Node %d, zone %8s", pgdat->node_id, zone->name);
1677         if (is_zone_first_populated(pgdat, zone)) {
1678                 seq_printf(m, "\n  per-node stats");
1679                 for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++) {
1680                         unsigned long pages = node_page_state_pages(pgdat, i);
1681
1682                         if (vmstat_item_print_in_thp(i))
1683                                 pages /= HPAGE_PMD_NR;
1684                         seq_printf(m, "\n      %-12s %lu", node_stat_name(i),
1685                                    pages);
1686                 }
1687         }
1688         seq_printf(m,
1689                    "\n  pages free     %lu"
1690                    "\n        boost    %lu"
1691                    "\n        min      %lu"
1692                    "\n        low      %lu"
1693                    "\n        high     %lu"
1694                    "\n        spanned  %lu"
1695                    "\n        present  %lu"
1696                    "\n        managed  %lu"
1697                    "\n        cma      %lu",
1698                    zone_page_state(zone, NR_FREE_PAGES),
1699                    zone->watermark_boost,
1700                    min_wmark_pages(zone),
1701                    low_wmark_pages(zone),
1702                    high_wmark_pages(zone),
1703                    zone->spanned_pages,
1704                    zone->present_pages,
1705                    zone_managed_pages(zone),
1706                    zone_cma_pages(zone));
1707
1708         seq_printf(m,
1709                    "\n        protection: (%ld",
1710                    zone->lowmem_reserve[0]);
1711         for (i = 1; i < ARRAY_SIZE(zone->lowmem_reserve); i++)
1712                 seq_printf(m, ", %ld", zone->lowmem_reserve[i]);
1713         seq_putc(m, ')');
1714
1715         /* If unpopulated, no other information is useful */
1716         if (!populated_zone(zone)) {
1717                 seq_putc(m, '\n');
1718                 return;
1719         }
1720
1721         for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
1722                 seq_printf(m, "\n      %-12s %lu", zone_stat_name(i),
1723                            zone_page_state(zone, i));
1724
1725 #ifdef CONFIG_NUMA
1726         for (i = 0; i < NR_VM_NUMA_EVENT_ITEMS; i++)
1727                 seq_printf(m, "\n      %-12s %lu", numa_stat_name(i),
1728                            zone_numa_event_state(zone, i));
1729 #endif
1730
1731         seq_printf(m, "\n  pagesets");
1732         for_each_online_cpu(i) {
1733                 struct per_cpu_pages *pcp;
1734                 struct per_cpu_zonestat __maybe_unused *pzstats;
1735
1736                 pcp = per_cpu_ptr(zone->per_cpu_pageset, i);
1737                 seq_printf(m,
1738                            "\n    cpu: %i"
1739                            "\n              count: %i"
1740                            "\n              high:  %i"
1741                            "\n              batch: %i",
1742                            i,
1743                            pcp->count,
1744                            pcp->high,
1745                            pcp->batch);
1746 #ifdef CONFIG_SMP
1747                 pzstats = per_cpu_ptr(zone->per_cpu_zonestats, i);
1748                 seq_printf(m, "\n  vm stats threshold: %d",
1749                                 pzstats->stat_threshold);
1750 #endif
1751         }
1752         seq_printf(m,
1753                    "\n  node_unreclaimable:  %u"
1754                    "\n  start_pfn:           %lu",
1755                    pgdat->kswapd_failures >= MAX_RECLAIM_RETRIES,
1756                    zone->zone_start_pfn);
1757         seq_putc(m, '\n');
1758 }
1759
1760 /*
1761  * Output information about zones in @pgdat.  All zones are printed regardless
1762  * of whether they are populated or not: lowmem_reserve_ratio operates on the
1763  * set of all zones and userspace would not be aware of such zones if they are
1764  * suppressed here (zoneinfo displays the effect of lowmem_reserve_ratio).
1765  */
1766 static int zoneinfo_show(struct seq_file *m, void *arg)
1767 {
1768         pg_data_t *pgdat = (pg_data_t *)arg;
1769         walk_zones_in_node(m, pgdat, false, false, zoneinfo_show_print);
1770         return 0;
1771 }
1772
1773 static const struct seq_operations zoneinfo_op = {
1774         .start  = frag_start, /* iterate over all zones. The same as in
1775                                * fragmentation. */
1776         .next   = frag_next,
1777         .stop   = frag_stop,
1778         .show   = zoneinfo_show,
1779 };
1780
1781 #define NR_VMSTAT_ITEMS (NR_VM_ZONE_STAT_ITEMS + \
1782                          NR_VM_NUMA_EVENT_ITEMS + \
1783                          NR_VM_NODE_STAT_ITEMS + \
1784                          NR_VM_WRITEBACK_STAT_ITEMS + \
1785                          (IS_ENABLED(CONFIG_VM_EVENT_COUNTERS) ? \
1786                           NR_VM_EVENT_ITEMS : 0))
1787
1788 static void *vmstat_start(struct seq_file *m, loff_t *pos)
1789 {
1790         unsigned long *v;
1791         int i;
1792
1793         if (*pos >= NR_VMSTAT_ITEMS)
1794                 return NULL;
1795
1796         BUILD_BUG_ON(ARRAY_SIZE(vmstat_text) < NR_VMSTAT_ITEMS);
1797         fold_vm_numa_events();
1798         v = kmalloc_array(NR_VMSTAT_ITEMS, sizeof(unsigned long), GFP_KERNEL);
1799         m->private = v;
1800         if (!v)
1801                 return ERR_PTR(-ENOMEM);
1802         for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
1803                 v[i] = global_zone_page_state(i);
1804         v += NR_VM_ZONE_STAT_ITEMS;
1805
1806 #ifdef CONFIG_NUMA
1807         for (i = 0; i < NR_VM_NUMA_EVENT_ITEMS; i++)
1808                 v[i] = global_numa_event_state(i);
1809         v += NR_VM_NUMA_EVENT_ITEMS;
1810 #endif
1811
1812         for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++) {
1813                 v[i] = global_node_page_state_pages(i);
1814                 if (vmstat_item_print_in_thp(i))
1815                         v[i] /= HPAGE_PMD_NR;
1816         }
1817         v += NR_VM_NODE_STAT_ITEMS;
1818
1819         global_dirty_limits(v + NR_DIRTY_BG_THRESHOLD,
1820                             v + NR_DIRTY_THRESHOLD);
1821         v += NR_VM_WRITEBACK_STAT_ITEMS;
1822
1823 #ifdef CONFIG_VM_EVENT_COUNTERS
1824         all_vm_events(v);
1825         v[PGPGIN] /= 2;         /* sectors -> kbytes */
1826         v[PGPGOUT] /= 2;
1827 #endif
1828         return (unsigned long *)m->private + *pos;
1829 }
1830
1831 static void *vmstat_next(struct seq_file *m, void *arg, loff_t *pos)
1832 {
1833         (*pos)++;
1834         if (*pos >= NR_VMSTAT_ITEMS)
1835                 return NULL;
1836         return (unsigned long *)m->private + *pos;
1837 }
1838
1839 static int vmstat_show(struct seq_file *m, void *arg)
1840 {
1841         unsigned long *l = arg;
1842         unsigned long off = l - (unsigned long *)m->private;
1843
1844         seq_puts(m, vmstat_text[off]);
1845         seq_put_decimal_ull(m, " ", *l);
1846         seq_putc(m, '\n');
1847
1848         if (off == NR_VMSTAT_ITEMS - 1) {
1849                 /*
1850                  * We've come to the end - add any deprecated counters to avoid
1851                  * breaking userspace which might depend on them being present.
1852                  */
1853                 seq_puts(m, "nr_unstable 0\n");
1854         }
1855         return 0;
1856 }
1857
1858 static void vmstat_stop(struct seq_file *m, void *arg)
1859 {
1860         kfree(m->private);
1861         m->private = NULL;
1862 }
1863
1864 static const struct seq_operations vmstat_op = {
1865         .start  = vmstat_start,
1866         .next   = vmstat_next,
1867         .stop   = vmstat_stop,
1868         .show   = vmstat_show,
1869 };
1870 #endif /* CONFIG_PROC_FS */
1871
1872 #ifdef CONFIG_SMP
1873 static DEFINE_PER_CPU(struct delayed_work, vmstat_work);
1874 int sysctl_stat_interval __read_mostly = HZ;
1875
1876 #ifdef CONFIG_PROC_FS
1877 static void refresh_vm_stats(struct work_struct *work)
1878 {
1879         refresh_cpu_vm_stats(true);
1880 }
1881
1882 int vmstat_refresh(struct ctl_table *table, int write,
1883                    void *buffer, size_t *lenp, loff_t *ppos)
1884 {
1885         long val;
1886         int err;
1887         int i;
1888
1889         /*
1890          * The regular update, every sysctl_stat_interval, may come later
1891          * than expected: leaving a significant amount in per_cpu buckets.
1892          * This is particularly misleading when checking a quantity of HUGE
1893          * pages, immediately after running a test.  /proc/sys/vm/stat_refresh,
1894          * which can equally be echo'ed to or cat'ted from (by root),
1895          * can be used to update the stats just before reading them.
1896          *
1897          * Oh, and since global_zone_page_state() etc. are so careful to hide
1898          * transiently negative values, report an error here if any of
1899          * the stats is negative, so we know to go looking for imbalance.
1900          */
1901         err = schedule_on_each_cpu(refresh_vm_stats);
1902         if (err)
1903                 return err;
1904         for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++) {
1905                 /*
1906                  * Skip checking stats known to go negative occasionally.
1907                  */
1908                 switch (i) {
1909                 case NR_ZONE_WRITE_PENDING:
1910                 case NR_FREE_CMA_PAGES:
1911                         continue;
1912                 }
1913                 val = atomic_long_read(&vm_zone_stat[i]);
1914                 if (val < 0) {
1915                         pr_warn("%s: %s %ld\n",
1916                                 __func__, zone_stat_name(i), val);
1917                 }
1918         }
1919         for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++) {
1920                 /*
1921                  * Skip checking stats known to go negative occasionally.
1922                  */
1923                 switch (i) {
1924                 case NR_WRITEBACK:
1925                         continue;
1926                 }
1927                 val = atomic_long_read(&vm_node_stat[i]);
1928                 if (val < 0) {
1929                         pr_warn("%s: %s %ld\n",
1930                                 __func__, node_stat_name(i), val);
1931                 }
1932         }
1933         if (write)
1934                 *ppos += *lenp;
1935         else
1936                 *lenp = 0;
1937         return 0;
1938 }
1939 #endif /* CONFIG_PROC_FS */
1940
1941 static void vmstat_update(struct work_struct *w)
1942 {
1943         if (refresh_cpu_vm_stats(true)) {
1944                 /*
1945                  * Counters were updated so we expect more updates
1946                  * to occur in the future. Keep on running the
1947                  * update worker thread.
1948                  */
1949                 queue_delayed_work_on(smp_processor_id(), mm_percpu_wq,
1950                                 this_cpu_ptr(&vmstat_work),
1951                                 round_jiffies_relative(sysctl_stat_interval));
1952         }
1953 }
1954
1955 /*
1956  * Check if the diffs for a certain cpu indicate that
1957  * an update is needed.
1958  */
1959 static bool need_update(int cpu)
1960 {
1961         pg_data_t *last_pgdat = NULL;
1962         struct zone *zone;
1963
1964         for_each_populated_zone(zone) {
1965                 struct per_cpu_zonestat *pzstats = per_cpu_ptr(zone->per_cpu_zonestats, cpu);
1966                 struct per_cpu_nodestat *n;
1967
1968                 /*
1969                  * The fast way of checking if there are any vmstat diffs.
1970                  */
1971                 if (memchr_inv(pzstats->vm_stat_diff, 0, sizeof(pzstats->vm_stat_diff)))
1972                         return true;
1973
1974                 if (last_pgdat == zone->zone_pgdat)
1975                         continue;
1976                 last_pgdat = zone->zone_pgdat;
1977                 n = per_cpu_ptr(zone->zone_pgdat->per_cpu_nodestats, cpu);
1978                 if (memchr_inv(n->vm_node_stat_diff, 0, sizeof(n->vm_node_stat_diff)))
1979                         return true;
1980         }
1981         return false;
1982 }
1983
1984 /*
1985  * Switch off vmstat processing and then fold all the remaining differentials
1986  * until the diffs stay at zero. The function is used by NOHZ and can only be
1987  * invoked when tick processing is not active.
1988  */
1989 void quiet_vmstat(void)
1990 {
1991         if (system_state != SYSTEM_RUNNING)
1992                 return;
1993
1994         if (!delayed_work_pending(this_cpu_ptr(&vmstat_work)))
1995                 return;
1996
1997         if (!need_update(smp_processor_id()))
1998                 return;
1999
2000         /*
2001          * Just refresh counters and do not care about the pending delayed
2002          * vmstat_update. It doesn't fire that often to matter and canceling
2003          * it would be too expensive from this path.
2004          * vmstat_shepherd will take care about that for us.
2005          */
2006         refresh_cpu_vm_stats(false);
2007 }
2008
2009 /*
2010  * Shepherd worker thread that checks the
2011  * differentials of processors that have their worker
2012  * threads for vm statistics updates disabled because of
2013  * inactivity.
2014  */
2015 static void vmstat_shepherd(struct work_struct *w);
2016
2017 static DECLARE_DEFERRABLE_WORK(shepherd, vmstat_shepherd);
2018
2019 static void vmstat_shepherd(struct work_struct *w)
2020 {
2021         int cpu;
2022
2023         cpus_read_lock();
2024         /* Check processors whose vmstat worker threads have been disabled */
2025         for_each_online_cpu(cpu) {
2026                 struct delayed_work *dw = &per_cpu(vmstat_work, cpu);
2027
2028                 /*
2029                  * In kernel users of vmstat counters either require the precise value and
2030                  * they are using zone_page_state_snapshot interface or they can live with
2031                  * an imprecision as the regular flushing can happen at arbitrary time and
2032                  * cumulative error can grow (see calculate_normal_threshold).
2033                  *
2034                  * From that POV the regular flushing can be postponed for CPUs that have
2035                  * been isolated from the kernel interference without critical
2036                  * infrastructure ever noticing. Skip regular flushing from vmstat_shepherd
2037                  * for all isolated CPUs to avoid interference with the isolated workload.
2038                  */
2039                 if (cpu_is_isolated(cpu))
2040                         continue;
2041
2042                 if (!delayed_work_pending(dw) && need_update(cpu))
2043                         queue_delayed_work_on(cpu, mm_percpu_wq, dw, 0);
2044
2045                 cond_resched();
2046         }
2047         cpus_read_unlock();
2048
2049         schedule_delayed_work(&shepherd,
2050                 round_jiffies_relative(sysctl_stat_interval));
2051 }
2052
2053 static void __init start_shepherd_timer(void)
2054 {
2055         int cpu;
2056
2057         for_each_possible_cpu(cpu)
2058                 INIT_DEFERRABLE_WORK(per_cpu_ptr(&vmstat_work, cpu),
2059                         vmstat_update);
2060
2061         schedule_delayed_work(&shepherd,
2062                 round_jiffies_relative(sysctl_stat_interval));
2063 }
2064
2065 static void __init init_cpu_node_state(void)
2066 {
2067         int node;
2068
2069         for_each_online_node(node) {
2070                 if (!cpumask_empty(cpumask_of_node(node)))
2071                         node_set_state(node, N_CPU);
2072         }
2073 }
2074
2075 static int vmstat_cpu_online(unsigned int cpu)
2076 {
2077         refresh_zone_stat_thresholds();
2078
2079         if (!node_state(cpu_to_node(cpu), N_CPU)) {
2080                 node_set_state(cpu_to_node(cpu), N_CPU);
2081         }
2082
2083         return 0;
2084 }
2085
2086 static int vmstat_cpu_down_prep(unsigned int cpu)
2087 {
2088         cancel_delayed_work_sync(&per_cpu(vmstat_work, cpu));
2089         return 0;
2090 }
2091
2092 static int vmstat_cpu_dead(unsigned int cpu)
2093 {
2094         const struct cpumask *node_cpus;
2095         int node;
2096
2097         node = cpu_to_node(cpu);
2098
2099         refresh_zone_stat_thresholds();
2100         node_cpus = cpumask_of_node(node);
2101         if (!cpumask_empty(node_cpus))
2102                 return 0;
2103
2104         node_clear_state(node, N_CPU);
2105
2106         return 0;
2107 }
2108
2109 #endif
2110
2111 struct workqueue_struct *mm_percpu_wq;
2112
2113 void __init init_mm_internals(void)
2114 {
2115         int ret __maybe_unused;
2116
2117         mm_percpu_wq = alloc_workqueue("mm_percpu_wq", WQ_MEM_RECLAIM, 0);
2118
2119 #ifdef CONFIG_SMP
2120         ret = cpuhp_setup_state_nocalls(CPUHP_MM_VMSTAT_DEAD, "mm/vmstat:dead",
2121                                         NULL, vmstat_cpu_dead);
2122         if (ret < 0)
2123                 pr_err("vmstat: failed to register 'dead' hotplug state\n");
2124
2125         ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "mm/vmstat:online",
2126                                         vmstat_cpu_online,
2127                                         vmstat_cpu_down_prep);
2128         if (ret < 0)
2129                 pr_err("vmstat: failed to register 'online' hotplug state\n");
2130
2131         cpus_read_lock();
2132         init_cpu_node_state();
2133         cpus_read_unlock();
2134
2135         start_shepherd_timer();
2136 #endif
2137 #ifdef CONFIG_PROC_FS
2138         proc_create_seq("buddyinfo", 0444, NULL, &fragmentation_op);
2139         proc_create_seq("pagetypeinfo", 0400, NULL, &pagetypeinfo_op);
2140         proc_create_seq("vmstat", 0444, NULL, &vmstat_op);
2141         proc_create_seq("zoneinfo", 0444, NULL, &zoneinfo_op);
2142 #endif
2143 }
2144
2145 #if defined(CONFIG_DEBUG_FS) && defined(CONFIG_COMPACTION)
2146
2147 /*
2148  * Return an index indicating how much of the available free memory is
2149  * unusable for an allocation of the requested size.
2150  */
2151 static int unusable_free_index(unsigned int order,
2152                                 struct contig_page_info *info)
2153 {
2154         /* No free memory is interpreted as all free memory is unusable */
2155         if (info->free_pages == 0)
2156                 return 1000;
2157
2158         /*
2159          * Index should be a value between 0 and 1. Return a value to 3
2160          * decimal places.
2161          *
2162          * 0 => no fragmentation
2163          * 1 => high fragmentation
2164          */
2165         return div_u64((info->free_pages - (info->free_blocks_suitable << order)) * 1000ULL, info->free_pages);
2166
2167 }
2168
2169 static void unusable_show_print(struct seq_file *m,
2170                                         pg_data_t *pgdat, struct zone *zone)
2171 {
2172         unsigned int order;
2173         int index;
2174         struct contig_page_info info;
2175
2176         seq_printf(m, "Node %d, zone %8s ",
2177                                 pgdat->node_id,
2178                                 zone->name);
2179         for (order = 0; order <= MAX_ORDER; ++order) {
2180                 fill_contig_page_info(zone, order, &info);
2181                 index = unusable_free_index(order, &info);
2182                 seq_printf(m, "%d.%03d ", index / 1000, index % 1000);
2183         }
2184
2185         seq_putc(m, '\n');
2186 }
2187
2188 /*
2189  * Display unusable free space index
2190  *
2191  * The unusable free space index measures how much of the available free
2192  * memory cannot be used to satisfy an allocation of a given size and is a
2193  * value between 0 and 1. The higher the value, the more of free memory is
2194  * unusable and by implication, the worse the external fragmentation is. This
2195  * can be expressed as a percentage by multiplying by 100.
2196  */
2197 static int unusable_show(struct seq_file *m, void *arg)
2198 {
2199         pg_data_t *pgdat = (pg_data_t *)arg;
2200
2201         /* check memoryless node */
2202         if (!node_state(pgdat->node_id, N_MEMORY))
2203                 return 0;
2204
2205         walk_zones_in_node(m, pgdat, true, false, unusable_show_print);
2206
2207         return 0;
2208 }
2209
2210 static const struct seq_operations unusable_sops = {
2211         .start  = frag_start,
2212         .next   = frag_next,
2213         .stop   = frag_stop,
2214         .show   = unusable_show,
2215 };
2216
2217 DEFINE_SEQ_ATTRIBUTE(unusable);
2218
2219 static void extfrag_show_print(struct seq_file *m,
2220                                         pg_data_t *pgdat, struct zone *zone)
2221 {
2222         unsigned int order;
2223         int index;
2224
2225         /* Alloc on stack as interrupts are disabled for zone walk */
2226         struct contig_page_info info;
2227
2228         seq_printf(m, "Node %d, zone %8s ",
2229                                 pgdat->node_id,
2230                                 zone->name);
2231         for (order = 0; order <= MAX_ORDER; ++order) {
2232                 fill_contig_page_info(zone, order, &info);
2233                 index = __fragmentation_index(order, &info);
2234                 seq_printf(m, "%2d.%03d ", index / 1000, index % 1000);
2235         }
2236
2237         seq_putc(m, '\n');
2238 }
2239
2240 /*
2241  * Display fragmentation index for orders that allocations would fail for
2242  */
2243 static int extfrag_show(struct seq_file *m, void *arg)
2244 {
2245         pg_data_t *pgdat = (pg_data_t *)arg;
2246
2247         walk_zones_in_node(m, pgdat, true, false, extfrag_show_print);
2248
2249         return 0;
2250 }
2251
2252 static const struct seq_operations extfrag_sops = {
2253         .start  = frag_start,
2254         .next   = frag_next,
2255         .stop   = frag_stop,
2256         .show   = extfrag_show,
2257 };
2258
2259 DEFINE_SEQ_ATTRIBUTE(extfrag);
2260
2261 static int __init extfrag_debug_init(void)
2262 {
2263         struct dentry *extfrag_debug_root;
2264
2265         extfrag_debug_root = debugfs_create_dir("extfrag", NULL);
2266
2267         debugfs_create_file("unusable_index", 0444, extfrag_debug_root, NULL,
2268                             &unusable_fops);
2269
2270         debugfs_create_file("extfrag_index", 0444, extfrag_debug_root, NULL,
2271                             &extfrag_fops);
2272
2273         return 0;
2274 }
2275
2276 module_init(extfrag_debug_init);
2277 #endif