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
  35int sysctl_vm_numa_stat = ENABLE_NUMA_STAT;
  36
  37/* zero numa counters within a zone */
  38static 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 */
  52static 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 */
  61static 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
  69static void invalid_numa_statistics(void)
  70{
  71	zero_zones_numa_counters();
  72	zero_global_numa_counters();
  73}
  74
  75static DEFINE_MUTEX(vm_numa_stat_lock);
  76
  77int 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
 100out:
 101	mutex_unlock(&vm_numa_stat_lock);
 102	return ret;
 103}
 104#endif
 105
 106#ifdef CONFIG_VM_EVENT_COUNTERS
 107DEFINE_PER_CPU(struct vm_event_state, vm_event_states) = {{0}};
 108EXPORT_PER_CPU_SYMBOL(vm_event_states);
 109
 110static 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*/
 130void all_vm_events(unsigned long *ret)
 131{
 132	cpus_read_lock();
 133	sum_vm_events(ret);
 134	cpus_read_unlock();
 135}
 136EXPORT_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 */
 144void 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 */
 162atomic_long_t vm_zone_stat[NR_VM_ZONE_STAT_ITEMS] __cacheline_aligned_in_smp;
 163atomic_long_t vm_node_stat[NR_VM_NODE_STAT_ITEMS] __cacheline_aligned_in_smp;
 164atomic_long_t vm_numa_event[NR_VM_NUMA_EVENT_ITEMS] __cacheline_aligned_in_smp;
 165EXPORT_SYMBOL(vm_zone_stat);
 166EXPORT_SYMBOL(vm_node_stat);
 167
 168#ifdef CONFIG_NUMA
 169static 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
 187void 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
 198int 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
 222int 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 */
 272void 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
 317void 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 */
 342void __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}
 371EXPORT_SYMBOL(__mod_zone_page_state);
 372
 373void __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}
 407EXPORT_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 */
 432void __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
 453void __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
 476void __inc_zone_page_state(struct page *page, enum zone_stat_item item)
 477{
 478	__inc_zone_state(page_zone(page), item);
 479}
 480EXPORT_SYMBOL(__inc_zone_page_state);
 481
 482void __inc_node_page_state(struct page *page, enum node_stat_item item)
 483{
 484	__inc_node_state(page_pgdat(page), item);
 485}
 486EXPORT_SYMBOL(__inc_node_page_state);
 487
 488void __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
 509void __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
 532void __dec_zone_page_state(struct page *page, enum zone_stat_item item)
 533{
 534	__dec_zone_state(page_zone(page), item);
 535}
 536EXPORT_SYMBOL(__dec_zone_page_state);
 537
 538void __dec_node_page_state(struct page *page, enum node_stat_item item)
 539{
 540	__dec_node_state(page_pgdat(page), item);
 541}
 542EXPORT_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*/
 557static 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 n, t, z;
 563	s8 o;
 564
 565	o = this_cpu_read(*p);
 566	do {
 567		z = 0;  /* overflow to zone counters */
 568
 569		/*
 570		 * The fetching of the stat_threshold is racy. We may apply
 571		 * a counter threshold to the wrong the cpu if we get
 572		 * rescheduled while executing here. However, the next
 573		 * counter update will apply the threshold again and
 574		 * therefore bring the counter under the threshold again.
 575		 *
 576		 * Most of the time the thresholds are the same anyways
 577		 * for all cpus in a zone.
 578		 */
 579		t = this_cpu_read(pcp->stat_threshold);
 580
 581		n = delta + (long)o;
 
 582
 583		if (abs(n) > t) {
 584			int os = overstep_mode * (t >> 1) ;
 585
 586			/* Overflow must be added to zone counters */
 587			z = n + os;
 588			n = -os;
 589		}
 590	} while (!this_cpu_try_cmpxchg(*p, &o, n));
 591
 592	if (z)
 593		zone_page_state_add(z, zone, item);
 594}
 595
 596void mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
 597			 long delta)
 598{
 599	mod_zone_state(zone, item, delta, 0);
 600}
 601EXPORT_SYMBOL(mod_zone_page_state);
 602
 603void inc_zone_page_state(struct page *page, enum zone_stat_item item)
 604{
 605	mod_zone_state(page_zone(page), item, 1, 1);
 606}
 607EXPORT_SYMBOL(inc_zone_page_state);
 608
 609void dec_zone_page_state(struct page *page, enum zone_stat_item item)
 610{
 611	mod_zone_state(page_zone(page), item, -1, -1);
 612}
 613EXPORT_SYMBOL(dec_zone_page_state);
 614
 615static inline void mod_node_state(struct pglist_data *pgdat,
 616       enum node_stat_item item, int delta, int overstep_mode)
 617{
 618	struct per_cpu_nodestat __percpu *pcp = pgdat->per_cpu_nodestats;
 619	s8 __percpu *p = pcp->vm_node_stat_diff + item;
 620	long n, t, z;
 621	s8 o;
 622
 623	if (vmstat_item_in_bytes(item)) {
 624		/*
 625		 * Only cgroups use subpage accounting right now; at
 626		 * the global level, these items still change in
 627		 * multiples of whole pages. Store them as pages
 628		 * internally to keep the per-cpu counters compact.
 629		 */
 630		VM_WARN_ON_ONCE(delta & (PAGE_SIZE - 1));
 631		delta >>= PAGE_SHIFT;
 632	}
 633
 634	o = this_cpu_read(*p);
 635	do {
 636		z = 0;  /* overflow to node counters */
 637
 638		/*
 639		 * The fetching of the stat_threshold is racy. We may apply
 640		 * a counter threshold to the wrong the cpu if we get
 641		 * rescheduled while executing here. However, the next
 642		 * counter update will apply the threshold again and
 643		 * therefore bring the counter under the threshold again.
 644		 *
 645		 * Most of the time the thresholds are the same anyways
 646		 * for all cpus in a node.
 647		 */
 648		t = this_cpu_read(pcp->stat_threshold);
 649
 650		n = delta + (long)o;
 
 651
 652		if (abs(n) > t) {
 653			int os = overstep_mode * (t >> 1) ;
 654
 655			/* Overflow must be added to node counters */
 656			z = n + os;
 657			n = -os;
 658		}
 659	} while (!this_cpu_try_cmpxchg(*p, &o, n));
 660
 661	if (z)
 662		node_page_state_add(z, pgdat, item);
 663}
 664
 665void mod_node_page_state(struct pglist_data *pgdat, enum node_stat_item item,
 666					long delta)
 667{
 668	mod_node_state(pgdat, item, delta, 0);
 669}
 670EXPORT_SYMBOL(mod_node_page_state);
 671
 672void inc_node_state(struct pglist_data *pgdat, enum node_stat_item item)
 673{
 674	mod_node_state(pgdat, item, 1, 1);
 675}
 676
 677void inc_node_page_state(struct page *page, enum node_stat_item item)
 678{
 679	mod_node_state(page_pgdat(page), item, 1, 1);
 680}
 681EXPORT_SYMBOL(inc_node_page_state);
 682
 683void dec_node_page_state(struct page *page, enum node_stat_item item)
 684{
 685	mod_node_state(page_pgdat(page), item, -1, -1);
 686}
 687EXPORT_SYMBOL(dec_node_page_state);
 688#else
 689/*
 690 * Use interrupt disable to serialize counter updates
 691 */
 692void mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
 693			 long delta)
 694{
 695	unsigned long flags;
 696
 697	local_irq_save(flags);
 698	__mod_zone_page_state(zone, item, delta);
 699	local_irq_restore(flags);
 700}
 701EXPORT_SYMBOL(mod_zone_page_state);
 702
 703void inc_zone_page_state(struct page *page, enum zone_stat_item item)
 704{
 705	unsigned long flags;
 706	struct zone *zone;
 707
 708	zone = page_zone(page);
 709	local_irq_save(flags);
 710	__inc_zone_state(zone, item);
 711	local_irq_restore(flags);
 712}
 713EXPORT_SYMBOL(inc_zone_page_state);
 714
 715void dec_zone_page_state(struct page *page, enum zone_stat_item item)
 716{
 717	unsigned long flags;
 718
 719	local_irq_save(flags);
 720	__dec_zone_page_state(page, item);
 721	local_irq_restore(flags);
 722}
 723EXPORT_SYMBOL(dec_zone_page_state);
 724
 725void inc_node_state(struct pglist_data *pgdat, enum node_stat_item item)
 726{
 727	unsigned long flags;
 728
 729	local_irq_save(flags);
 730	__inc_node_state(pgdat, item);
 731	local_irq_restore(flags);
 732}
 733EXPORT_SYMBOL(inc_node_state);
 734
 735void mod_node_page_state(struct pglist_data *pgdat, enum node_stat_item item,
 736					long delta)
 737{
 738	unsigned long flags;
 739
 740	local_irq_save(flags);
 741	__mod_node_page_state(pgdat, item, delta);
 742	local_irq_restore(flags);
 743}
 744EXPORT_SYMBOL(mod_node_page_state);
 745
 746void inc_node_page_state(struct page *page, enum node_stat_item item)
 747{
 748	unsigned long flags;
 749	struct pglist_data *pgdat;
 750
 751	pgdat = page_pgdat(page);
 752	local_irq_save(flags);
 753	__inc_node_state(pgdat, item);
 754	local_irq_restore(flags);
 755}
 756EXPORT_SYMBOL(inc_node_page_state);
 757
 758void dec_node_page_state(struct page *page, enum node_stat_item item)
 759{
 760	unsigned long flags;
 761
 762	local_irq_save(flags);
 763	__dec_node_page_state(page, item);
 764	local_irq_restore(flags);
 765}
 766EXPORT_SYMBOL(dec_node_page_state);
 767#endif
 768
 769/*
 770 * Fold a differential into the global counters.
 771 * Returns the number of counters updated.
 772 */
 773static int fold_diff(int *zone_diff, int *node_diff)
 774{
 775	int i;
 776	int changes = 0;
 777
 778	for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
 779		if (zone_diff[i]) {
 780			atomic_long_add(zone_diff[i], &vm_zone_stat[i]);
 781			changes++;
 782	}
 783
 784	for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++)
 785		if (node_diff[i]) {
 786			atomic_long_add(node_diff[i], &vm_node_stat[i]);
 787			changes++;
 788	}
 789	return changes;
 790}
 791
 792/*
 793 * Update the zone counters for the current cpu.
 794 *
 795 * Note that refresh_cpu_vm_stats strives to only access
 796 * node local memory. The per cpu pagesets on remote zones are placed
 797 * in the memory local to the processor using that pageset. So the
 798 * loop over all zones will access a series of cachelines local to
 799 * the processor.
 800 *
 801 * The call to zone_page_state_add updates the cachelines with the
 802 * statistics in the remote zone struct as well as the global cachelines
 803 * with the global counters. These could cause remote node cache line
 804 * bouncing and will have to be only done when necessary.
 805 *
 806 * The function returns the number of global counters updated.
 807 */
 808static int refresh_cpu_vm_stats(bool do_pagesets)
 809{
 810	struct pglist_data *pgdat;
 811	struct zone *zone;
 812	int i;
 813	int global_zone_diff[NR_VM_ZONE_STAT_ITEMS] = { 0, };
 814	int global_node_diff[NR_VM_NODE_STAT_ITEMS] = { 0, };
 815	int changes = 0;
 816
 817	for_each_populated_zone(zone) {
 818		struct per_cpu_zonestat __percpu *pzstats = zone->per_cpu_zonestats;
 
 819		struct per_cpu_pages __percpu *pcp = zone->per_cpu_pageset;
 
 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
 836		if (do_pagesets) {
 837			cond_resched();
 838
 839			changes += decay_pcp_high(zone, this_cpu_ptr(pcp));
 840#ifdef CONFIG_NUMA
 841			/*
 842			 * Deal with draining the remote pageset of this
 843			 * processor
 844			 *
 845			 * Check if there are pages remaining in this pageset
 846			 * if not then there is nothing to expire.
 847			 */
 848			if (!__this_cpu_read(pcp->expire) ||
 849			       !__this_cpu_read(pcp->count))
 850				continue;
 851
 852			/*
 853			 * We never drain zones local to this processor.
 854			 */
 855			if (zone_to_nid(zone) == numa_node_id()) {
 856				__this_cpu_write(pcp->expire, 0);
 857				continue;
 858			}
 859
 860			if (__this_cpu_dec_return(pcp->expire)) {
 861				changes++;
 862				continue;
 863			}
 864
 865			if (__this_cpu_read(pcp->count)) {
 866				drain_zone_pages(zone, this_cpu_ptr(pcp));
 867				changes++;
 868			}
 869#endif
 870		}
 
 871	}
 872
 873	for_each_online_pgdat(pgdat) {
 874		struct per_cpu_nodestat __percpu *p = pgdat->per_cpu_nodestats;
 875
 876		for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++) {
 877			int v;
 878
 879			v = this_cpu_xchg(p->vm_node_stat_diff[i], 0);
 880			if (v) {
 881				atomic_long_add(v, &pgdat->vm_stat[i]);
 882				global_node_diff[i] += v;
 883			}
 884		}
 885	}
 886
 887	changes += fold_diff(global_zone_diff, global_node_diff);
 888	return changes;
 889}
 890
 891/*
 892 * Fold the data for an offline cpu into the global array.
 893 * There cannot be any access by the offline cpu and therefore
 894 * synchronization is simplified.
 895 */
 896void cpu_vm_stats_fold(int cpu)
 897{
 898	struct pglist_data *pgdat;
 899	struct zone *zone;
 900	int i;
 901	int global_zone_diff[NR_VM_ZONE_STAT_ITEMS] = { 0, };
 902	int global_node_diff[NR_VM_NODE_STAT_ITEMS] = { 0, };
 903
 904	for_each_populated_zone(zone) {
 905		struct per_cpu_zonestat *pzstats;
 906
 907		pzstats = per_cpu_ptr(zone->per_cpu_zonestats, cpu);
 908
 909		for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++) {
 910			if (pzstats->vm_stat_diff[i]) {
 911				int v;
 912
 913				v = pzstats->vm_stat_diff[i];
 914				pzstats->vm_stat_diff[i] = 0;
 915				atomic_long_add(v, &zone->vm_stat[i]);
 916				global_zone_diff[i] += v;
 917			}
 918		}
 919#ifdef CONFIG_NUMA
 920		for (i = 0; i < NR_VM_NUMA_EVENT_ITEMS; i++) {
 921			if (pzstats->vm_numa_event[i]) {
 922				unsigned long v;
 923
 924				v = pzstats->vm_numa_event[i];
 925				pzstats->vm_numa_event[i] = 0;
 926				zone_numa_event_add(v, zone, i);
 927			}
 928		}
 929#endif
 930	}
 931
 932	for_each_online_pgdat(pgdat) {
 933		struct per_cpu_nodestat *p;
 934
 935		p = per_cpu_ptr(pgdat->per_cpu_nodestats, cpu);
 936
 937		for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++)
 938			if (p->vm_node_stat_diff[i]) {
 939				int v;
 940
 941				v = p->vm_node_stat_diff[i];
 942				p->vm_node_stat_diff[i] = 0;
 943				atomic_long_add(v, &pgdat->vm_stat[i]);
 944				global_node_diff[i] += v;
 945			}
 946	}
 947
 948	fold_diff(global_zone_diff, global_node_diff);
 949}
 950
 951/*
 952 * this is only called if !populated_zone(zone), which implies no other users of
 953 * pset->vm_stat_diff[] exist.
 954 */
 955void drain_zonestat(struct zone *zone, struct per_cpu_zonestat *pzstats)
 956{
 957	unsigned long v;
 958	int i;
 959
 960	for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++) {
 961		if (pzstats->vm_stat_diff[i]) {
 962			v = pzstats->vm_stat_diff[i];
 963			pzstats->vm_stat_diff[i] = 0;
 964			zone_page_state_add(v, zone, i);
 965		}
 966	}
 967
 968#ifdef CONFIG_NUMA
 969	for (i = 0; i < NR_VM_NUMA_EVENT_ITEMS; i++) {
 970		if (pzstats->vm_numa_event[i]) {
 971			v = pzstats->vm_numa_event[i];
 972			pzstats->vm_numa_event[i] = 0;
 973			zone_numa_event_add(v, zone, i);
 974		}
 975	}
 976#endif
 977}
 978#endif
 979
 980#ifdef CONFIG_NUMA
 981/*
 982 * Determine the per node value of a stat item. This function
 983 * is called frequently in a NUMA machine, so try to be as
 984 * frugal as possible.
 985 */
 986unsigned long sum_zone_node_page_state(int node,
 987				 enum zone_stat_item item)
 988{
 989	struct zone *zones = NODE_DATA(node)->node_zones;
 990	int i;
 991	unsigned long count = 0;
 992
 993	for (i = 0; i < MAX_NR_ZONES; i++)
 994		count += zone_page_state(zones + i, item);
 995
 996	return count;
 997}
 998
 999/* Determine the per node value of a numa stat item. */
1000unsigned long sum_zone_numa_event_state(int node,
1001				 enum numa_stat_item item)
1002{
1003	struct zone *zones = NODE_DATA(node)->node_zones;
1004	unsigned long count = 0;
1005	int i;
1006
1007	for (i = 0; i < MAX_NR_ZONES; i++)
1008		count += zone_numa_event_state(zones + i, item);
1009
1010	return count;
1011}
1012
1013/*
1014 * Determine the per node value of a stat item.
1015 */
1016unsigned long node_page_state_pages(struct pglist_data *pgdat,
1017				    enum node_stat_item item)
1018{
1019	long x = atomic_long_read(&pgdat->vm_stat[item]);
1020#ifdef CONFIG_SMP
1021	if (x < 0)
1022		x = 0;
1023#endif
1024	return x;
1025}
1026
1027unsigned long node_page_state(struct pglist_data *pgdat,
1028			      enum node_stat_item item)
1029{
1030	VM_WARN_ON_ONCE(vmstat_item_in_bytes(item));
1031
1032	return node_page_state_pages(pgdat, item);
1033}
1034#endif
1035
1036#ifdef CONFIG_COMPACTION
1037
1038struct contig_page_info {
1039	unsigned long free_pages;
1040	unsigned long free_blocks_total;
1041	unsigned long free_blocks_suitable;
1042};
1043
1044/*
1045 * Calculate the number of free pages in a zone, how many contiguous
1046 * pages are free and how many are large enough to satisfy an allocation of
1047 * the target size. Note that this function makes no attempt to estimate
1048 * how many suitable free blocks there *might* be if MOVABLE pages were
1049 * migrated. Calculating that is possible, but expensive and can be
1050 * figured out from userspace
1051 */
1052static void fill_contig_page_info(struct zone *zone,
1053				unsigned int suitable_order,
1054				struct contig_page_info *info)
1055{
1056	unsigned int order;
1057
1058	info->free_pages = 0;
1059	info->free_blocks_total = 0;
1060	info->free_blocks_suitable = 0;
1061
1062	for (order = 0; order < NR_PAGE_ORDERS; order++) {
1063		unsigned long blocks;
1064
1065		/*
1066		 * Count number of free blocks.
1067		 *
1068		 * Access to nr_free is lockless as nr_free is used only for
1069		 * diagnostic purposes. Use data_race to avoid KCSAN warning.
1070		 */
1071		blocks = data_race(zone->free_area[order].nr_free);
1072		info->free_blocks_total += blocks;
1073
1074		/* Count free base pages */
1075		info->free_pages += blocks << order;
1076
1077		/* Count the suitable free blocks */
1078		if (order >= suitable_order)
1079			info->free_blocks_suitable += blocks <<
1080						(order - suitable_order);
1081	}
1082}
1083
1084/*
1085 * A fragmentation index only makes sense if an allocation of a requested
1086 * size would fail. If that is true, the fragmentation index indicates
1087 * whether external fragmentation or a lack of memory was the problem.
1088 * The value can be used to determine if page reclaim or compaction
1089 * should be used
1090 */
1091static int __fragmentation_index(unsigned int order, struct contig_page_info *info)
1092{
1093	unsigned long requested = 1UL << order;
1094
1095	if (WARN_ON_ONCE(order > MAX_PAGE_ORDER))
1096		return 0;
1097
1098	if (!info->free_blocks_total)
1099		return 0;
1100
1101	/* Fragmentation index only makes sense when a request would fail */
1102	if (info->free_blocks_suitable)
1103		return -1000;
1104
1105	/*
1106	 * Index is between 0 and 1 so return within 3 decimal places
1107	 *
1108	 * 0 => allocation would fail due to lack of memory
1109	 * 1 => allocation would fail due to fragmentation
1110	 */
1111	return 1000 - div_u64( (1000+(div_u64(info->free_pages * 1000ULL, requested))), info->free_blocks_total);
1112}
1113
1114/*
1115 * Calculates external fragmentation within a zone wrt the given order.
1116 * It is defined as the percentage of pages found in blocks of size
1117 * less than 1 << order. It returns values in range [0, 100].
1118 */
1119unsigned int extfrag_for_order(struct zone *zone, unsigned int order)
1120{
1121	struct contig_page_info info;
1122
1123	fill_contig_page_info(zone, order, &info);
1124	if (info.free_pages == 0)
1125		return 0;
1126
1127	return div_u64((info.free_pages -
1128			(info.free_blocks_suitable << order)) * 100,
1129			info.free_pages);
1130}
1131
1132/* Same as __fragmentation index but allocs contig_page_info on stack */
1133int fragmentation_index(struct zone *zone, unsigned int order)
1134{
1135	struct contig_page_info info;
1136
1137	fill_contig_page_info(zone, order, &info);
1138	return __fragmentation_index(order, &info);
1139}
1140#endif
1141
1142#if defined(CONFIG_PROC_FS) || defined(CONFIG_SYSFS) || \
1143    defined(CONFIG_NUMA) || defined(CONFIG_MEMCG)
1144#ifdef CONFIG_ZONE_DMA
1145#define TEXT_FOR_DMA(xx) xx "_dma",
1146#else
1147#define TEXT_FOR_DMA(xx)
1148#endif
1149
1150#ifdef CONFIG_ZONE_DMA32
1151#define TEXT_FOR_DMA32(xx) xx "_dma32",
1152#else
1153#define TEXT_FOR_DMA32(xx)
1154#endif
1155
1156#ifdef CONFIG_HIGHMEM
1157#define TEXT_FOR_HIGHMEM(xx) xx "_high",
1158#else
1159#define TEXT_FOR_HIGHMEM(xx)
1160#endif
1161
1162#ifdef CONFIG_ZONE_DEVICE
1163#define TEXT_FOR_DEVICE(xx) xx "_device",
1164#else
1165#define TEXT_FOR_DEVICE(xx)
1166#endif
1167
1168#define TEXTS_FOR_ZONES(xx) TEXT_FOR_DMA(xx) TEXT_FOR_DMA32(xx) xx "_normal", \
1169					TEXT_FOR_HIGHMEM(xx) xx "_movable", \
1170					TEXT_FOR_DEVICE(xx)
1171
1172const char * const vmstat_text[] = {
1173	/* enum zone_stat_item counters */
1174	"nr_free_pages",
1175	"nr_zone_inactive_anon",
1176	"nr_zone_active_anon",
1177	"nr_zone_inactive_file",
1178	"nr_zone_active_file",
1179	"nr_zone_unevictable",
1180	"nr_zone_write_pending",
1181	"nr_mlock",
1182	"nr_bounce",
1183#if IS_ENABLED(CONFIG_ZSMALLOC)
1184	"nr_zspages",
1185#endif
1186	"nr_free_cma",
1187#ifdef CONFIG_UNACCEPTED_MEMORY
1188	"nr_unaccepted",
1189#endif
1190
1191	/* enum numa_stat_item counters */
1192#ifdef CONFIG_NUMA
1193	"numa_hit",
1194	"numa_miss",
1195	"numa_foreign",
1196	"numa_interleave",
1197	"numa_local",
1198	"numa_other",
1199#endif
1200
1201	/* enum node_stat_item counters */
1202	"nr_inactive_anon",
1203	"nr_active_anon",
1204	"nr_inactive_file",
1205	"nr_active_file",
1206	"nr_unevictable",
1207	"nr_slab_reclaimable",
1208	"nr_slab_unreclaimable",
1209	"nr_isolated_anon",
1210	"nr_isolated_file",
1211	"workingset_nodes",
1212	"workingset_refault_anon",
1213	"workingset_refault_file",
1214	"workingset_activate_anon",
1215	"workingset_activate_file",
1216	"workingset_restore_anon",
1217	"workingset_restore_file",
1218	"workingset_nodereclaim",
1219	"nr_anon_pages",
1220	"nr_mapped",
1221	"nr_file_pages",
1222	"nr_dirty",
1223	"nr_writeback",
1224	"nr_writeback_temp",
1225	"nr_shmem",
1226	"nr_shmem_hugepages",
1227	"nr_shmem_pmdmapped",
1228	"nr_file_hugepages",
1229	"nr_file_pmdmapped",
1230	"nr_anon_transparent_hugepages",
1231	"nr_vmscan_write",
1232	"nr_vmscan_immediate_reclaim",
1233	"nr_dirtied",
1234	"nr_written",
1235	"nr_throttled_written",
1236	"nr_kernel_misc_reclaimable",
1237	"nr_foll_pin_acquired",
1238	"nr_foll_pin_released",
1239	"nr_kernel_stack",
1240#if IS_ENABLED(CONFIG_SHADOW_CALL_STACK)
1241	"nr_shadow_call_stack",
1242#endif
1243	"nr_page_table_pages",
1244	"nr_sec_page_table_pages",
1245#ifdef CONFIG_SWAP
1246	"nr_swapcached",
1247#endif
1248#ifdef CONFIG_NUMA_BALANCING
1249	"pgpromote_success",
1250	"pgpromote_candidate",
1251#endif
1252	"pgdemote_kswapd",
1253	"pgdemote_direct",
1254	"pgdemote_khugepaged",
1255
1256	/* enum writeback_stat_item counters */
1257	"nr_dirty_threshold",
1258	"nr_dirty_background_threshold",
1259
1260#if defined(CONFIG_VM_EVENT_COUNTERS) || defined(CONFIG_MEMCG)
1261	/* enum vm_event_item counters */
1262	"pgpgin",
1263	"pgpgout",
1264	"pswpin",
1265	"pswpout",
1266
1267	TEXTS_FOR_ZONES("pgalloc")
1268	TEXTS_FOR_ZONES("allocstall")
1269	TEXTS_FOR_ZONES("pgskip")
1270
1271	"pgfree",
1272	"pgactivate",
1273	"pgdeactivate",
1274	"pglazyfree",
1275
1276	"pgfault",
1277	"pgmajfault",
1278	"pglazyfreed",
1279
1280	"pgrefill",
1281	"pgreuse",
1282	"pgsteal_kswapd",
1283	"pgsteal_direct",
1284	"pgsteal_khugepaged",
 
 
 
1285	"pgscan_kswapd",
1286	"pgscan_direct",
1287	"pgscan_khugepaged",
1288	"pgscan_direct_throttle",
1289	"pgscan_anon",
1290	"pgscan_file",
1291	"pgsteal_anon",
1292	"pgsteal_file",
1293
1294#ifdef CONFIG_NUMA
1295	"zone_reclaim_failed",
1296#endif
1297	"pginodesteal",
1298	"slabs_scanned",
1299	"kswapd_inodesteal",
1300	"kswapd_low_wmark_hit_quickly",
1301	"kswapd_high_wmark_hit_quickly",
1302	"pageoutrun",
1303
1304	"pgrotated",
1305
1306	"drop_pagecache",
1307	"drop_slab",
1308	"oom_kill",
1309
1310#ifdef CONFIG_NUMA_BALANCING
1311	"numa_pte_updates",
1312	"numa_huge_pte_updates",
1313	"numa_hint_faults",
1314	"numa_hint_faults_local",
1315	"numa_pages_migrated",
1316#endif
1317#ifdef CONFIG_MIGRATION
1318	"pgmigrate_success",
1319	"pgmigrate_fail",
1320	"thp_migration_success",
1321	"thp_migration_fail",
1322	"thp_migration_split",
1323#endif
1324#ifdef CONFIG_COMPACTION
1325	"compact_migrate_scanned",
1326	"compact_free_scanned",
1327	"compact_isolated",
1328	"compact_stall",
1329	"compact_fail",
1330	"compact_success",
1331	"compact_daemon_wake",
1332	"compact_daemon_migrate_scanned",
1333	"compact_daemon_free_scanned",
1334#endif
1335
1336#ifdef CONFIG_HUGETLB_PAGE
1337	"htlb_buddy_alloc_success",
1338	"htlb_buddy_alloc_fail",
1339#endif
1340#ifdef CONFIG_CMA
1341	"cma_alloc_success",
1342	"cma_alloc_fail",
1343#endif
1344	"unevictable_pgs_culled",
1345	"unevictable_pgs_scanned",
1346	"unevictable_pgs_rescued",
1347	"unevictable_pgs_mlocked",
1348	"unevictable_pgs_munlocked",
1349	"unevictable_pgs_cleared",
1350	"unevictable_pgs_stranded",
1351
1352#ifdef CONFIG_TRANSPARENT_HUGEPAGE
1353	"thp_fault_alloc",
1354	"thp_fault_fallback",
1355	"thp_fault_fallback_charge",
1356	"thp_collapse_alloc",
1357	"thp_collapse_alloc_failed",
1358	"thp_file_alloc",
1359	"thp_file_fallback",
1360	"thp_file_fallback_charge",
1361	"thp_file_mapped",
1362	"thp_split_page",
1363	"thp_split_page_failed",
1364	"thp_deferred_split_page",
1365	"thp_split_pmd",
1366	"thp_scan_exceed_none_pte",
1367	"thp_scan_exceed_swap_pte",
1368	"thp_scan_exceed_share_pte",
1369#ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1370	"thp_split_pud",
1371#endif
1372	"thp_zero_page_alloc",
1373	"thp_zero_page_alloc_failed",
1374	"thp_swpout",
1375	"thp_swpout_fallback",
1376#endif
1377#ifdef CONFIG_MEMORY_BALLOON
1378	"balloon_inflate",
1379	"balloon_deflate",
1380#ifdef CONFIG_BALLOON_COMPACTION
1381	"balloon_migrate",
1382#endif
1383#endif /* CONFIG_MEMORY_BALLOON */
1384#ifdef CONFIG_DEBUG_TLBFLUSH
1385	"nr_tlb_remote_flush",
1386	"nr_tlb_remote_flush_received",
1387	"nr_tlb_local_flush_all",
1388	"nr_tlb_local_flush_one",
1389#endif /* CONFIG_DEBUG_TLBFLUSH */
1390
1391#ifdef CONFIG_SWAP
1392	"swap_ra",
1393	"swap_ra_hit",
1394#ifdef CONFIG_KSM
1395	"ksm_swpin_copy",
1396#endif
1397#endif
1398#ifdef CONFIG_KSM
1399	"cow_ksm",
1400#endif
1401#ifdef CONFIG_ZSWAP
1402	"zswpin",
1403	"zswpout",
1404	"zswpwb",
1405#endif
1406#ifdef CONFIG_X86
1407	"direct_map_level2_splits",
1408	"direct_map_level3_splits",
1409#endif
1410#ifdef CONFIG_PER_VMA_LOCK_STATS
1411	"vma_lock_success",
1412	"vma_lock_abort",
1413	"vma_lock_retry",
1414	"vma_lock_miss",
1415#endif
1416#endif /* CONFIG_VM_EVENT_COUNTERS || CONFIG_MEMCG */
1417};
1418#endif /* CONFIG_PROC_FS || CONFIG_SYSFS || CONFIG_NUMA || CONFIG_MEMCG */
1419
1420#if (defined(CONFIG_DEBUG_FS) && defined(CONFIG_COMPACTION)) || \
1421     defined(CONFIG_PROC_FS)
1422static void *frag_start(struct seq_file *m, loff_t *pos)
1423{
1424	pg_data_t *pgdat;
1425	loff_t node = *pos;
1426
1427	for (pgdat = first_online_pgdat();
1428	     pgdat && node;
1429	     pgdat = next_online_pgdat(pgdat))
1430		--node;
1431
1432	return pgdat;
1433}
1434
1435static void *frag_next(struct seq_file *m, void *arg, loff_t *pos)
1436{
1437	pg_data_t *pgdat = (pg_data_t *)arg;
1438
1439	(*pos)++;
1440	return next_online_pgdat(pgdat);
1441}
1442
1443static void frag_stop(struct seq_file *m, void *arg)
1444{
1445}
1446
1447/*
1448 * Walk zones in a node and print using a callback.
1449 * If @assert_populated is true, only use callback for zones that are populated.
1450 */
1451static void walk_zones_in_node(struct seq_file *m, pg_data_t *pgdat,
1452		bool assert_populated, bool nolock,
1453		void (*print)(struct seq_file *m, pg_data_t *, struct zone *))
1454{
1455	struct zone *zone;
1456	struct zone *node_zones = pgdat->node_zones;
1457	unsigned long flags;
1458
1459	for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
1460		if (assert_populated && !populated_zone(zone))
1461			continue;
1462
1463		if (!nolock)
1464			spin_lock_irqsave(&zone->lock, flags);
1465		print(m, pgdat, zone);
1466		if (!nolock)
1467			spin_unlock_irqrestore(&zone->lock, flags);
1468	}
1469}
1470#endif
1471
1472#ifdef CONFIG_PROC_FS
1473static void frag_show_print(struct seq_file *m, pg_data_t *pgdat,
1474						struct zone *zone)
1475{
1476	int order;
1477
1478	seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
1479	for (order = 0; order < NR_PAGE_ORDERS; ++order)
1480		/*
1481		 * Access to nr_free is lockless as nr_free is used only for
1482		 * printing purposes. Use data_race to avoid KCSAN warning.
1483		 */
1484		seq_printf(m, "%6lu ", data_race(zone->free_area[order].nr_free));
1485	seq_putc(m, '\n');
1486}
1487
1488/*
1489 * This walks the free areas for each zone.
1490 */
1491static int frag_show(struct seq_file *m, void *arg)
1492{
1493	pg_data_t *pgdat = (pg_data_t *)arg;
1494	walk_zones_in_node(m, pgdat, true, false, frag_show_print);
1495	return 0;
1496}
1497
1498static void pagetypeinfo_showfree_print(struct seq_file *m,
1499					pg_data_t *pgdat, struct zone *zone)
1500{
1501	int order, mtype;
1502
1503	for (mtype = 0; mtype < MIGRATE_TYPES; mtype++) {
1504		seq_printf(m, "Node %4d, zone %8s, type %12s ",
1505					pgdat->node_id,
1506					zone->name,
1507					migratetype_names[mtype]);
1508		for (order = 0; order < NR_PAGE_ORDERS; ++order) {
1509			unsigned long freecount = 0;
1510			struct free_area *area;
1511			struct list_head *curr;
1512			bool overflow = false;
1513
1514			area = &(zone->free_area[order]);
1515
1516			list_for_each(curr, &area->free_list[mtype]) {
1517				/*
1518				 * Cap the free_list iteration because it might
1519				 * be really large and we are under a spinlock
1520				 * so a long time spent here could trigger a
1521				 * hard lockup detector. Anyway this is a
1522				 * debugging tool so knowing there is a handful
1523				 * of pages of this order should be more than
1524				 * sufficient.
1525				 */
1526				if (++freecount >= 100000) {
1527					overflow = true;
1528					break;
1529				}
1530			}
1531			seq_printf(m, "%s%6lu ", overflow ? ">" : "", freecount);
1532			spin_unlock_irq(&zone->lock);
1533			cond_resched();
1534			spin_lock_irq(&zone->lock);
1535		}
1536		seq_putc(m, '\n');
1537	}
1538}
1539
1540/* Print out the free pages at each order for each migatetype */
1541static void pagetypeinfo_showfree(struct seq_file *m, void *arg)
1542{
1543	int order;
1544	pg_data_t *pgdat = (pg_data_t *)arg;
1545
1546	/* Print header */
1547	seq_printf(m, "%-43s ", "Free pages count per migrate type at order");
1548	for (order = 0; order < NR_PAGE_ORDERS; ++order)
1549		seq_printf(m, "%6d ", order);
1550	seq_putc(m, '\n');
1551
1552	walk_zones_in_node(m, pgdat, true, false, pagetypeinfo_showfree_print);
1553}
1554
1555static void pagetypeinfo_showblockcount_print(struct seq_file *m,
1556					pg_data_t *pgdat, struct zone *zone)
1557{
1558	int mtype;
1559	unsigned long pfn;
1560	unsigned long start_pfn = zone->zone_start_pfn;
1561	unsigned long end_pfn = zone_end_pfn(zone);
1562	unsigned long count[MIGRATE_TYPES] = { 0, };
1563
1564	for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
1565		struct page *page;
1566
1567		page = pfn_to_online_page(pfn);
1568		if (!page)
1569			continue;
1570
1571		if (page_zone(page) != zone)
1572			continue;
1573
1574		mtype = get_pageblock_migratetype(page);
1575
1576		if (mtype < MIGRATE_TYPES)
1577			count[mtype]++;
1578	}
1579
1580	/* Print counts */
1581	seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
1582	for (mtype = 0; mtype < MIGRATE_TYPES; mtype++)
1583		seq_printf(m, "%12lu ", count[mtype]);
1584	seq_putc(m, '\n');
1585}
1586
1587/* Print out the number of pageblocks for each migratetype */
1588static void pagetypeinfo_showblockcount(struct seq_file *m, void *arg)
1589{
1590	int mtype;
1591	pg_data_t *pgdat = (pg_data_t *)arg;
1592
1593	seq_printf(m, "\n%-23s", "Number of blocks type ");
1594	for (mtype = 0; mtype < MIGRATE_TYPES; mtype++)
1595		seq_printf(m, "%12s ", migratetype_names[mtype]);
1596	seq_putc(m, '\n');
1597	walk_zones_in_node(m, pgdat, true, false,
1598		pagetypeinfo_showblockcount_print);
1599}
1600
1601/*
1602 * Print out the number of pageblocks for each migratetype that contain pages
1603 * of other types. This gives an indication of how well fallbacks are being
1604 * contained by rmqueue_fallback(). It requires information from PAGE_OWNER
1605 * to determine what is going on
1606 */
1607static void pagetypeinfo_showmixedcount(struct seq_file *m, pg_data_t *pgdat)
1608{
1609#ifdef CONFIG_PAGE_OWNER
1610	int mtype;
1611
1612	if (!static_branch_unlikely(&page_owner_inited))
1613		return;
1614
1615	drain_all_pages(NULL);
1616
1617	seq_printf(m, "\n%-23s", "Number of mixed blocks ");
1618	for (mtype = 0; mtype < MIGRATE_TYPES; mtype++)
1619		seq_printf(m, "%12s ", migratetype_names[mtype]);
1620	seq_putc(m, '\n');
1621
1622	walk_zones_in_node(m, pgdat, true, true,
1623		pagetypeinfo_showmixedcount_print);
1624#endif /* CONFIG_PAGE_OWNER */
1625}
1626
1627/*
1628 * This prints out statistics in relation to grouping pages by mobility.
1629 * It is expensive to collect so do not constantly read the file.
1630 */
1631static int pagetypeinfo_show(struct seq_file *m, void *arg)
1632{
1633	pg_data_t *pgdat = (pg_data_t *)arg;
1634
1635	/* check memoryless node */
1636	if (!node_state(pgdat->node_id, N_MEMORY))
1637		return 0;
1638
1639	seq_printf(m, "Page block order: %d\n", pageblock_order);
1640	seq_printf(m, "Pages per block:  %lu\n", pageblock_nr_pages);
1641	seq_putc(m, '\n');
1642	pagetypeinfo_showfree(m, pgdat);
1643	pagetypeinfo_showblockcount(m, pgdat);
1644	pagetypeinfo_showmixedcount(m, pgdat);
1645
1646	return 0;
1647}
1648
1649static const struct seq_operations fragmentation_op = {
1650	.start	= frag_start,
1651	.next	= frag_next,
1652	.stop	= frag_stop,
1653	.show	= frag_show,
1654};
1655
1656static const struct seq_operations pagetypeinfo_op = {
1657	.start	= frag_start,
1658	.next	= frag_next,
1659	.stop	= frag_stop,
1660	.show	= pagetypeinfo_show,
1661};
1662
1663static bool is_zone_first_populated(pg_data_t *pgdat, struct zone *zone)
1664{
1665	int zid;
1666
1667	for (zid = 0; zid < MAX_NR_ZONES; zid++) {
1668		struct zone *compare = &pgdat->node_zones[zid];
1669
1670		if (populated_zone(compare))
1671			return zone == compare;
1672	}
1673
1674	return false;
1675}
1676
1677static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
1678							struct zone *zone)
1679{
1680	int i;
1681	seq_printf(m, "Node %d, zone %8s", pgdat->node_id, zone->name);
1682	if (is_zone_first_populated(pgdat, zone)) {
1683		seq_printf(m, "\n  per-node stats");
1684		for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++) {
1685			unsigned long pages = node_page_state_pages(pgdat, i);
1686
1687			if (vmstat_item_print_in_thp(i))
1688				pages /= HPAGE_PMD_NR;
1689			seq_printf(m, "\n      %-12s %lu", node_stat_name(i),
1690				   pages);
1691		}
1692	}
1693	seq_printf(m,
1694		   "\n  pages free     %lu"
1695		   "\n        boost    %lu"
1696		   "\n        min      %lu"
1697		   "\n        low      %lu"
1698		   "\n        high     %lu"
1699		   "\n        spanned  %lu"
1700		   "\n        present  %lu"
1701		   "\n        managed  %lu"
1702		   "\n        cma      %lu",
1703		   zone_page_state(zone, NR_FREE_PAGES),
1704		   zone->watermark_boost,
1705		   min_wmark_pages(zone),
1706		   low_wmark_pages(zone),
1707		   high_wmark_pages(zone),
1708		   zone->spanned_pages,
1709		   zone->present_pages,
1710		   zone_managed_pages(zone),
1711		   zone_cma_pages(zone));
1712
1713	seq_printf(m,
1714		   "\n        protection: (%ld",
1715		   zone->lowmem_reserve[0]);
1716	for (i = 1; i < ARRAY_SIZE(zone->lowmem_reserve); i++)
1717		seq_printf(m, ", %ld", zone->lowmem_reserve[i]);
1718	seq_putc(m, ')');
1719
1720	/* If unpopulated, no other information is useful */
1721	if (!populated_zone(zone)) {
1722		seq_putc(m, '\n');
1723		return;
1724	}
1725
1726	for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
1727		seq_printf(m, "\n      %-12s %lu", zone_stat_name(i),
1728			   zone_page_state(zone, i));
1729
1730#ifdef CONFIG_NUMA
1731	for (i = 0; i < NR_VM_NUMA_EVENT_ITEMS; i++)
1732		seq_printf(m, "\n      %-12s %lu", numa_stat_name(i),
1733			   zone_numa_event_state(zone, i));
1734#endif
1735
1736	seq_printf(m, "\n  pagesets");
1737	for_each_online_cpu(i) {
1738		struct per_cpu_pages *pcp;
1739		struct per_cpu_zonestat __maybe_unused *pzstats;
1740
1741		pcp = per_cpu_ptr(zone->per_cpu_pageset, i);
1742		seq_printf(m,
1743			   "\n    cpu: %i"
1744			   "\n              count: %i"
1745			   "\n              high:  %i"
1746			   "\n              batch: %i",
1747			   i,
1748			   pcp->count,
1749			   pcp->high,
1750			   pcp->batch);
1751#ifdef CONFIG_SMP
1752		pzstats = per_cpu_ptr(zone->per_cpu_zonestats, i);
1753		seq_printf(m, "\n  vm stats threshold: %d",
1754				pzstats->stat_threshold);
1755#endif
1756	}
1757	seq_printf(m,
1758		   "\n  node_unreclaimable:  %u"
1759		   "\n  start_pfn:           %lu",
1760		   pgdat->kswapd_failures >= MAX_RECLAIM_RETRIES,
1761		   zone->zone_start_pfn);
1762	seq_putc(m, '\n');
1763}
1764
1765/*
1766 * Output information about zones in @pgdat.  All zones are printed regardless
1767 * of whether they are populated or not: lowmem_reserve_ratio operates on the
1768 * set of all zones and userspace would not be aware of such zones if they are
1769 * suppressed here (zoneinfo displays the effect of lowmem_reserve_ratio).
1770 */
1771static int zoneinfo_show(struct seq_file *m, void *arg)
1772{
1773	pg_data_t *pgdat = (pg_data_t *)arg;
1774	walk_zones_in_node(m, pgdat, false, false, zoneinfo_show_print);
1775	return 0;
1776}
1777
1778static const struct seq_operations zoneinfo_op = {
1779	.start	= frag_start, /* iterate over all zones. The same as in
1780			       * fragmentation. */
1781	.next	= frag_next,
1782	.stop	= frag_stop,
1783	.show	= zoneinfo_show,
1784};
1785
1786#define NR_VMSTAT_ITEMS (NR_VM_ZONE_STAT_ITEMS + \
1787			 NR_VM_NUMA_EVENT_ITEMS + \
1788			 NR_VM_NODE_STAT_ITEMS + \
1789			 NR_VM_WRITEBACK_STAT_ITEMS + \
1790			 (IS_ENABLED(CONFIG_VM_EVENT_COUNTERS) ? \
1791			  NR_VM_EVENT_ITEMS : 0))
1792
1793static void *vmstat_start(struct seq_file *m, loff_t *pos)
1794{
1795	unsigned long *v;
1796	int i;
1797
1798	if (*pos >= NR_VMSTAT_ITEMS)
1799		return NULL;
1800
1801	BUILD_BUG_ON(ARRAY_SIZE(vmstat_text) < NR_VMSTAT_ITEMS);
1802	fold_vm_numa_events();
1803	v = kmalloc_array(NR_VMSTAT_ITEMS, sizeof(unsigned long), GFP_KERNEL);
1804	m->private = v;
1805	if (!v)
1806		return ERR_PTR(-ENOMEM);
1807	for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
1808		v[i] = global_zone_page_state(i);
1809	v += NR_VM_ZONE_STAT_ITEMS;
1810
1811#ifdef CONFIG_NUMA
1812	for (i = 0; i < NR_VM_NUMA_EVENT_ITEMS; i++)
1813		v[i] = global_numa_event_state(i);
1814	v += NR_VM_NUMA_EVENT_ITEMS;
1815#endif
1816
1817	for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++) {
1818		v[i] = global_node_page_state_pages(i);
1819		if (vmstat_item_print_in_thp(i))
1820			v[i] /= HPAGE_PMD_NR;
1821	}
1822	v += NR_VM_NODE_STAT_ITEMS;
1823
1824	global_dirty_limits(v + NR_DIRTY_BG_THRESHOLD,
1825			    v + NR_DIRTY_THRESHOLD);
1826	v += NR_VM_WRITEBACK_STAT_ITEMS;
1827
1828#ifdef CONFIG_VM_EVENT_COUNTERS
1829	all_vm_events(v);
1830	v[PGPGIN] /= 2;		/* sectors -> kbytes */
1831	v[PGPGOUT] /= 2;
1832#endif
1833	return (unsigned long *)m->private + *pos;
1834}
1835
1836static void *vmstat_next(struct seq_file *m, void *arg, loff_t *pos)
1837{
1838	(*pos)++;
1839	if (*pos >= NR_VMSTAT_ITEMS)
1840		return NULL;
1841	return (unsigned long *)m->private + *pos;
1842}
1843
1844static int vmstat_show(struct seq_file *m, void *arg)
1845{
1846	unsigned long *l = arg;
1847	unsigned long off = l - (unsigned long *)m->private;
1848
1849	seq_puts(m, vmstat_text[off]);
1850	seq_put_decimal_ull(m, " ", *l);
1851	seq_putc(m, '\n');
1852
1853	if (off == NR_VMSTAT_ITEMS - 1) {
1854		/*
1855		 * We've come to the end - add any deprecated counters to avoid
1856		 * breaking userspace which might depend on them being present.
1857		 */
1858		seq_puts(m, "nr_unstable 0\n");
1859	}
1860	return 0;
1861}
1862
1863static void vmstat_stop(struct seq_file *m, void *arg)
1864{
1865	kfree(m->private);
1866	m->private = NULL;
1867}
1868
1869static const struct seq_operations vmstat_op = {
1870	.start	= vmstat_start,
1871	.next	= vmstat_next,
1872	.stop	= vmstat_stop,
1873	.show	= vmstat_show,
1874};
1875#endif /* CONFIG_PROC_FS */
1876
1877#ifdef CONFIG_SMP
1878static DEFINE_PER_CPU(struct delayed_work, vmstat_work);
1879int sysctl_stat_interval __read_mostly = HZ;
1880
1881#ifdef CONFIG_PROC_FS
1882static void refresh_vm_stats(struct work_struct *work)
1883{
1884	refresh_cpu_vm_stats(true);
1885}
1886
1887int vmstat_refresh(struct ctl_table *table, int write,
1888		   void *buffer, size_t *lenp, loff_t *ppos)
1889{
1890	long val;
1891	int err;
1892	int i;
1893
1894	/*
1895	 * The regular update, every sysctl_stat_interval, may come later
1896	 * than expected: leaving a significant amount in per_cpu buckets.
1897	 * This is particularly misleading when checking a quantity of HUGE
1898	 * pages, immediately after running a test.  /proc/sys/vm/stat_refresh,
1899	 * which can equally be echo'ed to or cat'ted from (by root),
1900	 * can be used to update the stats just before reading them.
1901	 *
1902	 * Oh, and since global_zone_page_state() etc. are so careful to hide
1903	 * transiently negative values, report an error here if any of
1904	 * the stats is negative, so we know to go looking for imbalance.
1905	 */
1906	err = schedule_on_each_cpu(refresh_vm_stats);
1907	if (err)
1908		return err;
1909	for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++) {
1910		/*
1911		 * Skip checking stats known to go negative occasionally.
1912		 */
1913		switch (i) {
1914		case NR_ZONE_WRITE_PENDING:
1915		case NR_FREE_CMA_PAGES:
1916			continue;
1917		}
1918		val = atomic_long_read(&vm_zone_stat[i]);
1919		if (val < 0) {
1920			pr_warn("%s: %s %ld\n",
1921				__func__, zone_stat_name(i), val);
1922		}
1923	}
1924	for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++) {
1925		/*
1926		 * Skip checking stats known to go negative occasionally.
1927		 */
1928		switch (i) {
1929		case NR_WRITEBACK:
1930			continue;
1931		}
1932		val = atomic_long_read(&vm_node_stat[i]);
1933		if (val < 0) {
1934			pr_warn("%s: %s %ld\n",
1935				__func__, node_stat_name(i), val);
1936		}
1937	}
1938	if (write)
1939		*ppos += *lenp;
1940	else
1941		*lenp = 0;
1942	return 0;
1943}
1944#endif /* CONFIG_PROC_FS */
1945
1946static void vmstat_update(struct work_struct *w)
1947{
1948	if (refresh_cpu_vm_stats(true)) {
1949		/*
1950		 * Counters were updated so we expect more updates
1951		 * to occur in the future. Keep on running the
1952		 * update worker thread.
1953		 */
1954		queue_delayed_work_on(smp_processor_id(), mm_percpu_wq,
1955				this_cpu_ptr(&vmstat_work),
1956				round_jiffies_relative(sysctl_stat_interval));
1957	}
1958}
1959
1960/*
1961 * Check if the diffs for a certain cpu indicate that
1962 * an update is needed.
1963 */
1964static bool need_update(int cpu)
1965{
1966	pg_data_t *last_pgdat = NULL;
1967	struct zone *zone;
1968
1969	for_each_populated_zone(zone) {
1970		struct per_cpu_zonestat *pzstats = per_cpu_ptr(zone->per_cpu_zonestats, cpu);
1971		struct per_cpu_nodestat *n;
1972
1973		/*
1974		 * The fast way of checking if there are any vmstat diffs.
1975		 */
1976		if (memchr_inv(pzstats->vm_stat_diff, 0, sizeof(pzstats->vm_stat_diff)))
1977			return true;
1978
1979		if (last_pgdat == zone->zone_pgdat)
1980			continue;
1981		last_pgdat = zone->zone_pgdat;
1982		n = per_cpu_ptr(zone->zone_pgdat->per_cpu_nodestats, cpu);
1983		if (memchr_inv(n->vm_node_stat_diff, 0, sizeof(n->vm_node_stat_diff)))
1984			return true;
1985	}
1986	return false;
1987}
1988
1989/*
1990 * Switch off vmstat processing and then fold all the remaining differentials
1991 * until the diffs stay at zero. The function is used by NOHZ and can only be
1992 * invoked when tick processing is not active.
1993 */
1994void quiet_vmstat(void)
1995{
1996	if (system_state != SYSTEM_RUNNING)
1997		return;
1998
1999	if (!delayed_work_pending(this_cpu_ptr(&vmstat_work)))
2000		return;
2001
2002	if (!need_update(smp_processor_id()))
2003		return;
2004
2005	/*
2006	 * Just refresh counters and do not care about the pending delayed
2007	 * vmstat_update. It doesn't fire that often to matter and canceling
2008	 * it would be too expensive from this path.
2009	 * vmstat_shepherd will take care about that for us.
2010	 */
2011	refresh_cpu_vm_stats(false);
2012}
2013
2014/*
2015 * Shepherd worker thread that checks the
2016 * differentials of processors that have their worker
2017 * threads for vm statistics updates disabled because of
2018 * inactivity.
2019 */
2020static void vmstat_shepherd(struct work_struct *w);
2021
2022static DECLARE_DEFERRABLE_WORK(shepherd, vmstat_shepherd);
2023
2024static void vmstat_shepherd(struct work_struct *w)
2025{
2026	int cpu;
2027
2028	cpus_read_lock();
2029	/* Check processors whose vmstat worker threads have been disabled */
2030	for_each_online_cpu(cpu) {
2031		struct delayed_work *dw = &per_cpu(vmstat_work, cpu);
2032
2033		/*
2034		 * In kernel users of vmstat counters either require the precise value and
2035		 * they are using zone_page_state_snapshot interface or they can live with
2036		 * an imprecision as the regular flushing can happen at arbitrary time and
2037		 * cumulative error can grow (see calculate_normal_threshold).
2038		 *
2039		 * From that POV the regular flushing can be postponed for CPUs that have
2040		 * been isolated from the kernel interference without critical
2041		 * infrastructure ever noticing. Skip regular flushing from vmstat_shepherd
2042		 * for all isolated CPUs to avoid interference with the isolated workload.
2043		 */
2044		if (cpu_is_isolated(cpu))
2045			continue;
2046
2047		if (!delayed_work_pending(dw) && need_update(cpu))
2048			queue_delayed_work_on(cpu, mm_percpu_wq, dw, 0);
2049
2050		cond_resched();
2051	}
2052	cpus_read_unlock();
2053
2054	schedule_delayed_work(&shepherd,
2055		round_jiffies_relative(sysctl_stat_interval));
2056}
2057
2058static void __init start_shepherd_timer(void)
2059{
2060	int cpu;
2061
2062	for_each_possible_cpu(cpu)
2063		INIT_DEFERRABLE_WORK(per_cpu_ptr(&vmstat_work, cpu),
2064			vmstat_update);
2065
2066	schedule_delayed_work(&shepherd,
2067		round_jiffies_relative(sysctl_stat_interval));
2068}
2069
2070static void __init init_cpu_node_state(void)
2071{
2072	int node;
2073
2074	for_each_online_node(node) {
2075		if (!cpumask_empty(cpumask_of_node(node)))
2076			node_set_state(node, N_CPU);
2077	}
2078}
2079
2080static int vmstat_cpu_online(unsigned int cpu)
2081{
2082	refresh_zone_stat_thresholds();
2083
2084	if (!node_state(cpu_to_node(cpu), N_CPU)) {
2085		node_set_state(cpu_to_node(cpu), N_CPU);
2086	}
2087
2088	return 0;
2089}
2090
2091static int vmstat_cpu_down_prep(unsigned int cpu)
2092{
2093	cancel_delayed_work_sync(&per_cpu(vmstat_work, cpu));
2094	return 0;
2095}
2096
2097static int vmstat_cpu_dead(unsigned int cpu)
2098{
2099	const struct cpumask *node_cpus;
2100	int node;
2101
2102	node = cpu_to_node(cpu);
2103
2104	refresh_zone_stat_thresholds();
2105	node_cpus = cpumask_of_node(node);
2106	if (!cpumask_empty(node_cpus))
2107		return 0;
2108
2109	node_clear_state(node, N_CPU);
2110
2111	return 0;
2112}
2113
2114#endif
2115
2116struct workqueue_struct *mm_percpu_wq;
2117
2118void __init init_mm_internals(void)
2119{
2120	int ret __maybe_unused;
2121
2122	mm_percpu_wq = alloc_workqueue("mm_percpu_wq", WQ_MEM_RECLAIM, 0);
2123
2124#ifdef CONFIG_SMP
2125	ret = cpuhp_setup_state_nocalls(CPUHP_MM_VMSTAT_DEAD, "mm/vmstat:dead",
2126					NULL, vmstat_cpu_dead);
2127	if (ret < 0)
2128		pr_err("vmstat: failed to register 'dead' hotplug state\n");
2129
2130	ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "mm/vmstat:online",
2131					vmstat_cpu_online,
2132					vmstat_cpu_down_prep);
2133	if (ret < 0)
2134		pr_err("vmstat: failed to register 'online' hotplug state\n");
2135
2136	cpus_read_lock();
2137	init_cpu_node_state();
2138	cpus_read_unlock();
2139
2140	start_shepherd_timer();
2141#endif
2142#ifdef CONFIG_PROC_FS
2143	proc_create_seq("buddyinfo", 0444, NULL, &fragmentation_op);
2144	proc_create_seq("pagetypeinfo", 0400, NULL, &pagetypeinfo_op);
2145	proc_create_seq("vmstat", 0444, NULL, &vmstat_op);
2146	proc_create_seq("zoneinfo", 0444, NULL, &zoneinfo_op);
2147#endif
2148}
2149
2150#if defined(CONFIG_DEBUG_FS) && defined(CONFIG_COMPACTION)
2151
2152/*
2153 * Return an index indicating how much of the available free memory is
2154 * unusable for an allocation of the requested size.
2155 */
2156static int unusable_free_index(unsigned int order,
2157				struct contig_page_info *info)
2158{
2159	/* No free memory is interpreted as all free memory is unusable */
2160	if (info->free_pages == 0)
2161		return 1000;
2162
2163	/*
2164	 * Index should be a value between 0 and 1. Return a value to 3
2165	 * decimal places.
2166	 *
2167	 * 0 => no fragmentation
2168	 * 1 => high fragmentation
2169	 */
2170	return div_u64((info->free_pages - (info->free_blocks_suitable << order)) * 1000ULL, info->free_pages);
2171
2172}
2173
2174static void unusable_show_print(struct seq_file *m,
2175					pg_data_t *pgdat, struct zone *zone)
2176{
2177	unsigned int order;
2178	int index;
2179	struct contig_page_info info;
2180
2181	seq_printf(m, "Node %d, zone %8s ",
2182				pgdat->node_id,
2183				zone->name);
2184	for (order = 0; order < NR_PAGE_ORDERS; ++order) {
2185		fill_contig_page_info(zone, order, &info);
2186		index = unusable_free_index(order, &info);
2187		seq_printf(m, "%d.%03d ", index / 1000, index % 1000);
2188	}
2189
2190	seq_putc(m, '\n');
2191}
2192
2193/*
2194 * Display unusable free space index
2195 *
2196 * The unusable free space index measures how much of the available free
2197 * memory cannot be used to satisfy an allocation of a given size and is a
2198 * value between 0 and 1. The higher the value, the more of free memory is
2199 * unusable and by implication, the worse the external fragmentation is. This
2200 * can be expressed as a percentage by multiplying by 100.
2201 */
2202static int unusable_show(struct seq_file *m, void *arg)
2203{
2204	pg_data_t *pgdat = (pg_data_t *)arg;
2205
2206	/* check memoryless node */
2207	if (!node_state(pgdat->node_id, N_MEMORY))
2208		return 0;
2209
2210	walk_zones_in_node(m, pgdat, true, false, unusable_show_print);
2211
2212	return 0;
2213}
2214
2215static const struct seq_operations unusable_sops = {
2216	.start	= frag_start,
2217	.next	= frag_next,
2218	.stop	= frag_stop,
2219	.show	= unusable_show,
2220};
2221
2222DEFINE_SEQ_ATTRIBUTE(unusable);
2223
2224static void extfrag_show_print(struct seq_file *m,
2225					pg_data_t *pgdat, struct zone *zone)
2226{
2227	unsigned int order;
2228	int index;
2229
2230	/* Alloc on stack as interrupts are disabled for zone walk */
2231	struct contig_page_info info;
2232
2233	seq_printf(m, "Node %d, zone %8s ",
2234				pgdat->node_id,
2235				zone->name);
2236	for (order = 0; order < NR_PAGE_ORDERS; ++order) {
2237		fill_contig_page_info(zone, order, &info);
2238		index = __fragmentation_index(order, &info);
2239		seq_printf(m, "%2d.%03d ", index / 1000, index % 1000);
2240	}
2241
2242	seq_putc(m, '\n');
2243}
2244
2245/*
2246 * Display fragmentation index for orders that allocations would fail for
2247 */
2248static int extfrag_show(struct seq_file *m, void *arg)
2249{
2250	pg_data_t *pgdat = (pg_data_t *)arg;
2251
2252	walk_zones_in_node(m, pgdat, true, false, extfrag_show_print);
2253
2254	return 0;
2255}
2256
2257static const struct seq_operations extfrag_sops = {
2258	.start	= frag_start,
2259	.next	= frag_next,
2260	.stop	= frag_stop,
2261	.show	= extfrag_show,
2262};
2263
2264DEFINE_SEQ_ATTRIBUTE(extfrag);
2265
2266static int __init extfrag_debug_init(void)
2267{
2268	struct dentry *extfrag_debug_root;
2269
2270	extfrag_debug_root = debugfs_create_dir("extfrag", NULL);
2271
2272	debugfs_create_file("unusable_index", 0444, extfrag_debug_root, NULL,
2273			    &unusable_fops);
2274
2275	debugfs_create_file("extfrag_index", 0444, extfrag_debug_root, NULL,
2276			    &extfrag_fops);
2277
2278	return 0;
2279}
2280
2281module_init(extfrag_debug_init);
2282#endif