xref: /openbmc/linux/mm/vmstat.c (revision f8e17c17)
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_ext.h>
30 #include <linux/page_owner.h>
31 
32 #include "internal.h"
33 
34 #define NUMA_STATS_THRESHOLD (U16_MAX - 2)
35 
36 #ifdef CONFIG_NUMA
37 int sysctl_vm_numa_stat = ENABLE_NUMA_STAT;
38 
39 /* zero numa counters within a zone */
40 static void zero_zone_numa_counters(struct zone *zone)
41 {
42 	int item, cpu;
43 
44 	for (item = 0; item < NR_VM_NUMA_STAT_ITEMS; item++) {
45 		atomic_long_set(&zone->vm_numa_stat[item], 0);
46 		for_each_online_cpu(cpu)
47 			per_cpu_ptr(zone->pageset, cpu)->vm_numa_stat_diff[item]
48 						= 0;
49 	}
50 }
51 
52 /* zero numa counters of all the populated zones */
53 static void zero_zones_numa_counters(void)
54 {
55 	struct zone *zone;
56 
57 	for_each_populated_zone(zone)
58 		zero_zone_numa_counters(zone);
59 }
60 
61 /* zero global numa counters */
62 static void zero_global_numa_counters(void)
63 {
64 	int item;
65 
66 	for (item = 0; item < NR_VM_NUMA_STAT_ITEMS; item++)
67 		atomic_long_set(&vm_numa_stat[item], 0);
68 }
69 
70 static void invalid_numa_statistics(void)
71 {
72 	zero_zones_numa_counters();
73 	zero_global_numa_counters();
74 }
75 
76 static DEFINE_MUTEX(vm_numa_stat_lock);
77 
78 int sysctl_vm_numa_stat_handler(struct ctl_table *table, int write,
79 		void __user *buffer, size_t *length, loff_t *ppos)
80 {
81 	int ret, oldval;
82 
83 	mutex_lock(&vm_numa_stat_lock);
84 	if (write)
85 		oldval = sysctl_vm_numa_stat;
86 	ret = proc_dointvec_minmax(table, write, buffer, length, ppos);
87 	if (ret || !write)
88 		goto out;
89 
90 	if (oldval == sysctl_vm_numa_stat)
91 		goto out;
92 	else if (sysctl_vm_numa_stat == ENABLE_NUMA_STAT) {
93 		static_branch_enable(&vm_numa_stat_key);
94 		pr_info("enable numa statistics\n");
95 	} else {
96 		static_branch_disable(&vm_numa_stat_key);
97 		invalid_numa_statistics();
98 		pr_info("disable numa statistics, and clear numa counters\n");
99 	}
100 
101 out:
102 	mutex_unlock(&vm_numa_stat_lock);
103 	return ret;
104 }
105 #endif
106 
107 #ifdef CONFIG_VM_EVENT_COUNTERS
108 DEFINE_PER_CPU(struct vm_event_state, vm_event_states) = {{0}};
109 EXPORT_PER_CPU_SYMBOL(vm_event_states);
110 
111 static void sum_vm_events(unsigned long *ret)
112 {
113 	int cpu;
114 	int i;
115 
116 	memset(ret, 0, NR_VM_EVENT_ITEMS * sizeof(unsigned long));
117 
118 	for_each_online_cpu(cpu) {
119 		struct vm_event_state *this = &per_cpu(vm_event_states, cpu);
120 
121 		for (i = 0; i < NR_VM_EVENT_ITEMS; i++)
122 			ret[i] += this->event[i];
123 	}
124 }
125 
126 /*
127  * Accumulate the vm event counters across all CPUs.
128  * The result is unavoidably approximate - it can change
129  * during and after execution of this function.
130 */
131 void all_vm_events(unsigned long *ret)
132 {
133 	get_online_cpus();
134 	sum_vm_events(ret);
135 	put_online_cpus();
136 }
137 EXPORT_SYMBOL_GPL(all_vm_events);
138 
139 /*
140  * Fold the foreign cpu events into our own.
141  *
142  * This is adding to the events on one processor
143  * but keeps the global counts constant.
144  */
145 void vm_events_fold_cpu(int cpu)
146 {
147 	struct vm_event_state *fold_state = &per_cpu(vm_event_states, cpu);
148 	int i;
149 
150 	for (i = 0; i < NR_VM_EVENT_ITEMS; i++) {
151 		count_vm_events(i, fold_state->event[i]);
152 		fold_state->event[i] = 0;
153 	}
154 }
155 
156 #endif /* CONFIG_VM_EVENT_COUNTERS */
157 
158 /*
159  * Manage combined zone based / global counters
160  *
161  * vm_stat contains the global counters
162  */
163 atomic_long_t vm_zone_stat[NR_VM_ZONE_STAT_ITEMS] __cacheline_aligned_in_smp;
164 atomic_long_t vm_numa_stat[NR_VM_NUMA_STAT_ITEMS] __cacheline_aligned_in_smp;
165 atomic_long_t vm_node_stat[NR_VM_NODE_STAT_ITEMS] __cacheline_aligned_in_smp;
166 EXPORT_SYMBOL(vm_zone_stat);
167 EXPORT_SYMBOL(vm_numa_stat);
168 EXPORT_SYMBOL(vm_node_stat);
169 
170 #ifdef CONFIG_SMP
171 
172 int calculate_pressure_threshold(struct zone *zone)
173 {
174 	int threshold;
175 	int watermark_distance;
176 
177 	/*
178 	 * As vmstats are not up to date, there is drift between the estimated
179 	 * and real values. For high thresholds and a high number of CPUs, it
180 	 * is possible for the min watermark to be breached while the estimated
181 	 * value looks fine. The pressure threshold is a reduced value such
182 	 * that even the maximum amount of drift will not accidentally breach
183 	 * the min watermark
184 	 */
185 	watermark_distance = low_wmark_pages(zone) - min_wmark_pages(zone);
186 	threshold = max(1, (int)(watermark_distance / num_online_cpus()));
187 
188 	/*
189 	 * Maximum threshold is 125
190 	 */
191 	threshold = min(125, threshold);
192 
193 	return threshold;
194 }
195 
196 int calculate_normal_threshold(struct zone *zone)
197 {
198 	int threshold;
199 	int mem;	/* memory in 128 MB units */
200 
201 	/*
202 	 * The threshold scales with the number of processors and the amount
203 	 * of memory per zone. More memory means that we can defer updates for
204 	 * longer, more processors could lead to more contention.
205  	 * fls() is used to have a cheap way of logarithmic scaling.
206 	 *
207 	 * Some sample thresholds:
208 	 *
209 	 * Threshold	Processors	(fls)	Zonesize	fls(mem+1)
210 	 * ------------------------------------------------------------------
211 	 * 8		1		1	0.9-1 GB	4
212 	 * 16		2		2	0.9-1 GB	4
213 	 * 20 		2		2	1-2 GB		5
214 	 * 24		2		2	2-4 GB		6
215 	 * 28		2		2	4-8 GB		7
216 	 * 32		2		2	8-16 GB		8
217 	 * 4		2		2	<128M		1
218 	 * 30		4		3	2-4 GB		5
219 	 * 48		4		3	8-16 GB		8
220 	 * 32		8		4	1-2 GB		4
221 	 * 32		8		4	0.9-1GB		4
222 	 * 10		16		5	<128M		1
223 	 * 40		16		5	900M		4
224 	 * 70		64		7	2-4 GB		5
225 	 * 84		64		7	4-8 GB		6
226 	 * 108		512		9	4-8 GB		6
227 	 * 125		1024		10	8-16 GB		8
228 	 * 125		1024		10	16-32 GB	9
229 	 */
230 
231 	mem = zone_managed_pages(zone) >> (27 - PAGE_SHIFT);
232 
233 	threshold = 2 * fls(num_online_cpus()) * (1 + fls(mem));
234 
235 	/*
236 	 * Maximum threshold is 125
237 	 */
238 	threshold = min(125, threshold);
239 
240 	return threshold;
241 }
242 
243 /*
244  * Refresh the thresholds for each zone.
245  */
246 void refresh_zone_stat_thresholds(void)
247 {
248 	struct pglist_data *pgdat;
249 	struct zone *zone;
250 	int cpu;
251 	int threshold;
252 
253 	/* Zero current pgdat thresholds */
254 	for_each_online_pgdat(pgdat) {
255 		for_each_online_cpu(cpu) {
256 			per_cpu_ptr(pgdat->per_cpu_nodestats, cpu)->stat_threshold = 0;
257 		}
258 	}
259 
260 	for_each_populated_zone(zone) {
261 		struct pglist_data *pgdat = zone->zone_pgdat;
262 		unsigned long max_drift, tolerate_drift;
263 
264 		threshold = calculate_normal_threshold(zone);
265 
266 		for_each_online_cpu(cpu) {
267 			int pgdat_threshold;
268 
269 			per_cpu_ptr(zone->pageset, cpu)->stat_threshold
270 							= threshold;
271 
272 			/* Base nodestat threshold on the largest populated zone. */
273 			pgdat_threshold = per_cpu_ptr(pgdat->per_cpu_nodestats, cpu)->stat_threshold;
274 			per_cpu_ptr(pgdat->per_cpu_nodestats, cpu)->stat_threshold
275 				= max(threshold, pgdat_threshold);
276 		}
277 
278 		/*
279 		 * Only set percpu_drift_mark if there is a danger that
280 		 * NR_FREE_PAGES reports the low watermark is ok when in fact
281 		 * the min watermark could be breached by an allocation
282 		 */
283 		tolerate_drift = low_wmark_pages(zone) - min_wmark_pages(zone);
284 		max_drift = num_online_cpus() * threshold;
285 		if (max_drift > tolerate_drift)
286 			zone->percpu_drift_mark = high_wmark_pages(zone) +
287 					max_drift;
288 	}
289 }
290 
291 void set_pgdat_percpu_threshold(pg_data_t *pgdat,
292 				int (*calculate_pressure)(struct zone *))
293 {
294 	struct zone *zone;
295 	int cpu;
296 	int threshold;
297 	int i;
298 
299 	for (i = 0; i < pgdat->nr_zones; i++) {
300 		zone = &pgdat->node_zones[i];
301 		if (!zone->percpu_drift_mark)
302 			continue;
303 
304 		threshold = (*calculate_pressure)(zone);
305 		for_each_online_cpu(cpu)
306 			per_cpu_ptr(zone->pageset, cpu)->stat_threshold
307 							= threshold;
308 	}
309 }
310 
311 /*
312  * For use when we know that interrupts are disabled,
313  * or when we know that preemption is disabled and that
314  * particular counter cannot be updated from interrupt context.
315  */
316 void __mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
317 			   long delta)
318 {
319 	struct per_cpu_pageset __percpu *pcp = zone->pageset;
320 	s8 __percpu *p = pcp->vm_stat_diff + item;
321 	long x;
322 	long t;
323 
324 	x = delta + __this_cpu_read(*p);
325 
326 	t = __this_cpu_read(pcp->stat_threshold);
327 
328 	if (unlikely(x > t || x < -t)) {
329 		zone_page_state_add(x, zone, item);
330 		x = 0;
331 	}
332 	__this_cpu_write(*p, x);
333 }
334 EXPORT_SYMBOL(__mod_zone_page_state);
335 
336 void __mod_node_page_state(struct pglist_data *pgdat, enum node_stat_item item,
337 				long delta)
338 {
339 	struct per_cpu_nodestat __percpu *pcp = pgdat->per_cpu_nodestats;
340 	s8 __percpu *p = pcp->vm_node_stat_diff + item;
341 	long x;
342 	long t;
343 
344 	x = delta + __this_cpu_read(*p);
345 
346 	t = __this_cpu_read(pcp->stat_threshold);
347 
348 	if (unlikely(x > t || x < -t)) {
349 		node_page_state_add(x, pgdat, item);
350 		x = 0;
351 	}
352 	__this_cpu_write(*p, x);
353 }
354 EXPORT_SYMBOL(__mod_node_page_state);
355 
356 /*
357  * Optimized increment and decrement functions.
358  *
359  * These are only for a single page and therefore can take a struct page *
360  * argument instead of struct zone *. This allows the inclusion of the code
361  * generated for page_zone(page) into the optimized functions.
362  *
363  * No overflow check is necessary and therefore the differential can be
364  * incremented or decremented in place which may allow the compilers to
365  * generate better code.
366  * The increment or decrement is known and therefore one boundary check can
367  * be omitted.
368  *
369  * NOTE: These functions are very performance sensitive. Change only
370  * with care.
371  *
372  * Some processors have inc/dec instructions that are atomic vs an interrupt.
373  * However, the code must first determine the differential location in a zone
374  * based on the processor number and then inc/dec the counter. There is no
375  * guarantee without disabling preemption that the processor will not change
376  * in between and therefore the atomicity vs. interrupt cannot be exploited
377  * in a useful way here.
378  */
379 void __inc_zone_state(struct zone *zone, enum zone_stat_item item)
380 {
381 	struct per_cpu_pageset __percpu *pcp = zone->pageset;
382 	s8 __percpu *p = pcp->vm_stat_diff + item;
383 	s8 v, t;
384 
385 	v = __this_cpu_inc_return(*p);
386 	t = __this_cpu_read(pcp->stat_threshold);
387 	if (unlikely(v > t)) {
388 		s8 overstep = t >> 1;
389 
390 		zone_page_state_add(v + overstep, zone, item);
391 		__this_cpu_write(*p, -overstep);
392 	}
393 }
394 
395 void __inc_node_state(struct pglist_data *pgdat, enum node_stat_item item)
396 {
397 	struct per_cpu_nodestat __percpu *pcp = pgdat->per_cpu_nodestats;
398 	s8 __percpu *p = pcp->vm_node_stat_diff + item;
399 	s8 v, t;
400 
401 	v = __this_cpu_inc_return(*p);
402 	t = __this_cpu_read(pcp->stat_threshold);
403 	if (unlikely(v > t)) {
404 		s8 overstep = t >> 1;
405 
406 		node_page_state_add(v + overstep, pgdat, item);
407 		__this_cpu_write(*p, -overstep);
408 	}
409 }
410 
411 void __inc_zone_page_state(struct page *page, enum zone_stat_item item)
412 {
413 	__inc_zone_state(page_zone(page), item);
414 }
415 EXPORT_SYMBOL(__inc_zone_page_state);
416 
417 void __inc_node_page_state(struct page *page, enum node_stat_item item)
418 {
419 	__inc_node_state(page_pgdat(page), item);
420 }
421 EXPORT_SYMBOL(__inc_node_page_state);
422 
423 void __dec_zone_state(struct zone *zone, enum zone_stat_item item)
424 {
425 	struct per_cpu_pageset __percpu *pcp = zone->pageset;
426 	s8 __percpu *p = pcp->vm_stat_diff + item;
427 	s8 v, t;
428 
429 	v = __this_cpu_dec_return(*p);
430 	t = __this_cpu_read(pcp->stat_threshold);
431 	if (unlikely(v < - t)) {
432 		s8 overstep = t >> 1;
433 
434 		zone_page_state_add(v - overstep, zone, item);
435 		__this_cpu_write(*p, overstep);
436 	}
437 }
438 
439 void __dec_node_state(struct pglist_data *pgdat, enum node_stat_item item)
440 {
441 	struct per_cpu_nodestat __percpu *pcp = pgdat->per_cpu_nodestats;
442 	s8 __percpu *p = pcp->vm_node_stat_diff + item;
443 	s8 v, t;
444 
445 	v = __this_cpu_dec_return(*p);
446 	t = __this_cpu_read(pcp->stat_threshold);
447 	if (unlikely(v < - t)) {
448 		s8 overstep = t >> 1;
449 
450 		node_page_state_add(v - overstep, pgdat, item);
451 		__this_cpu_write(*p, overstep);
452 	}
453 }
454 
455 void __dec_zone_page_state(struct page *page, enum zone_stat_item item)
456 {
457 	__dec_zone_state(page_zone(page), item);
458 }
459 EXPORT_SYMBOL(__dec_zone_page_state);
460 
461 void __dec_node_page_state(struct page *page, enum node_stat_item item)
462 {
463 	__dec_node_state(page_pgdat(page), item);
464 }
465 EXPORT_SYMBOL(__dec_node_page_state);
466 
467 #ifdef CONFIG_HAVE_CMPXCHG_LOCAL
468 /*
469  * If we have cmpxchg_local support then we do not need to incur the overhead
470  * that comes with local_irq_save/restore if we use this_cpu_cmpxchg.
471  *
472  * mod_state() modifies the zone counter state through atomic per cpu
473  * operations.
474  *
475  * Overstep mode specifies how overstep should handled:
476  *     0       No overstepping
477  *     1       Overstepping half of threshold
478  *     -1      Overstepping minus half of threshold
479 */
480 static inline void mod_zone_state(struct zone *zone,
481        enum zone_stat_item item, long delta, int overstep_mode)
482 {
483 	struct per_cpu_pageset __percpu *pcp = zone->pageset;
484 	s8 __percpu *p = pcp->vm_stat_diff + item;
485 	long o, n, t, z;
486 
487 	do {
488 		z = 0;  /* overflow to zone counters */
489 
490 		/*
491 		 * The fetching of the stat_threshold is racy. We may apply
492 		 * a counter threshold to the wrong the cpu if we get
493 		 * rescheduled while executing here. However, the next
494 		 * counter update will apply the threshold again and
495 		 * therefore bring the counter under the threshold again.
496 		 *
497 		 * Most of the time the thresholds are the same anyways
498 		 * for all cpus in a zone.
499 		 */
500 		t = this_cpu_read(pcp->stat_threshold);
501 
502 		o = this_cpu_read(*p);
503 		n = delta + o;
504 
505 		if (n > t || n < -t) {
506 			int os = overstep_mode * (t >> 1) ;
507 
508 			/* Overflow must be added to zone counters */
509 			z = n + os;
510 			n = -os;
511 		}
512 	} while (this_cpu_cmpxchg(*p, o, n) != o);
513 
514 	if (z)
515 		zone_page_state_add(z, zone, item);
516 }
517 
518 void mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
519 			 long delta)
520 {
521 	mod_zone_state(zone, item, delta, 0);
522 }
523 EXPORT_SYMBOL(mod_zone_page_state);
524 
525 void inc_zone_page_state(struct page *page, enum zone_stat_item item)
526 {
527 	mod_zone_state(page_zone(page), item, 1, 1);
528 }
529 EXPORT_SYMBOL(inc_zone_page_state);
530 
531 void dec_zone_page_state(struct page *page, enum zone_stat_item item)
532 {
533 	mod_zone_state(page_zone(page), item, -1, -1);
534 }
535 EXPORT_SYMBOL(dec_zone_page_state);
536 
537 static inline void mod_node_state(struct pglist_data *pgdat,
538        enum node_stat_item item, int delta, int overstep_mode)
539 {
540 	struct per_cpu_nodestat __percpu *pcp = pgdat->per_cpu_nodestats;
541 	s8 __percpu *p = pcp->vm_node_stat_diff + item;
542 	long o, n, t, z;
543 
544 	do {
545 		z = 0;  /* overflow to node counters */
546 
547 		/*
548 		 * The fetching of the stat_threshold is racy. We may apply
549 		 * a counter threshold to the wrong the cpu if we get
550 		 * rescheduled while executing here. However, the next
551 		 * counter update will apply the threshold again and
552 		 * therefore bring the counter under the threshold again.
553 		 *
554 		 * Most of the time the thresholds are the same anyways
555 		 * for all cpus in a node.
556 		 */
557 		t = this_cpu_read(pcp->stat_threshold);
558 
559 		o = this_cpu_read(*p);
560 		n = delta + o;
561 
562 		if (n > t || n < -t) {
563 			int os = overstep_mode * (t >> 1) ;
564 
565 			/* Overflow must be added to node counters */
566 			z = n + os;
567 			n = -os;
568 		}
569 	} while (this_cpu_cmpxchg(*p, o, n) != o);
570 
571 	if (z)
572 		node_page_state_add(z, pgdat, item);
573 }
574 
575 void mod_node_page_state(struct pglist_data *pgdat, enum node_stat_item item,
576 					long delta)
577 {
578 	mod_node_state(pgdat, item, delta, 0);
579 }
580 EXPORT_SYMBOL(mod_node_page_state);
581 
582 void inc_node_state(struct pglist_data *pgdat, enum node_stat_item item)
583 {
584 	mod_node_state(pgdat, item, 1, 1);
585 }
586 
587 void inc_node_page_state(struct page *page, enum node_stat_item item)
588 {
589 	mod_node_state(page_pgdat(page), item, 1, 1);
590 }
591 EXPORT_SYMBOL(inc_node_page_state);
592 
593 void dec_node_page_state(struct page *page, enum node_stat_item item)
594 {
595 	mod_node_state(page_pgdat(page), item, -1, -1);
596 }
597 EXPORT_SYMBOL(dec_node_page_state);
598 #else
599 /*
600  * Use interrupt disable to serialize counter updates
601  */
602 void mod_zone_page_state(struct zone *zone, enum zone_stat_item item,
603 			 long delta)
604 {
605 	unsigned long flags;
606 
607 	local_irq_save(flags);
608 	__mod_zone_page_state(zone, item, delta);
609 	local_irq_restore(flags);
610 }
611 EXPORT_SYMBOL(mod_zone_page_state);
612 
613 void inc_zone_page_state(struct page *page, enum zone_stat_item item)
614 {
615 	unsigned long flags;
616 	struct zone *zone;
617 
618 	zone = page_zone(page);
619 	local_irq_save(flags);
620 	__inc_zone_state(zone, item);
621 	local_irq_restore(flags);
622 }
623 EXPORT_SYMBOL(inc_zone_page_state);
624 
625 void dec_zone_page_state(struct page *page, enum zone_stat_item item)
626 {
627 	unsigned long flags;
628 
629 	local_irq_save(flags);
630 	__dec_zone_page_state(page, item);
631 	local_irq_restore(flags);
632 }
633 EXPORT_SYMBOL(dec_zone_page_state);
634 
635 void inc_node_state(struct pglist_data *pgdat, enum node_stat_item item)
636 {
637 	unsigned long flags;
638 
639 	local_irq_save(flags);
640 	__inc_node_state(pgdat, item);
641 	local_irq_restore(flags);
642 }
643 EXPORT_SYMBOL(inc_node_state);
644 
645 void mod_node_page_state(struct pglist_data *pgdat, enum node_stat_item item,
646 					long delta)
647 {
648 	unsigned long flags;
649 
650 	local_irq_save(flags);
651 	__mod_node_page_state(pgdat, item, delta);
652 	local_irq_restore(flags);
653 }
654 EXPORT_SYMBOL(mod_node_page_state);
655 
656 void inc_node_page_state(struct page *page, enum node_stat_item item)
657 {
658 	unsigned long flags;
659 	struct pglist_data *pgdat;
660 
661 	pgdat = page_pgdat(page);
662 	local_irq_save(flags);
663 	__inc_node_state(pgdat, item);
664 	local_irq_restore(flags);
665 }
666 EXPORT_SYMBOL(inc_node_page_state);
667 
668 void dec_node_page_state(struct page *page, enum node_stat_item item)
669 {
670 	unsigned long flags;
671 
672 	local_irq_save(flags);
673 	__dec_node_page_state(page, item);
674 	local_irq_restore(flags);
675 }
676 EXPORT_SYMBOL(dec_node_page_state);
677 #endif
678 
679 /*
680  * Fold a differential into the global counters.
681  * Returns the number of counters updated.
682  */
683 #ifdef CONFIG_NUMA
684 static int fold_diff(int *zone_diff, int *numa_diff, int *node_diff)
685 {
686 	int i;
687 	int changes = 0;
688 
689 	for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
690 		if (zone_diff[i]) {
691 			atomic_long_add(zone_diff[i], &vm_zone_stat[i]);
692 			changes++;
693 	}
694 
695 	for (i = 0; i < NR_VM_NUMA_STAT_ITEMS; i++)
696 		if (numa_diff[i]) {
697 			atomic_long_add(numa_diff[i], &vm_numa_stat[i]);
698 			changes++;
699 	}
700 
701 	for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++)
702 		if (node_diff[i]) {
703 			atomic_long_add(node_diff[i], &vm_node_stat[i]);
704 			changes++;
705 	}
706 	return changes;
707 }
708 #else
709 static int fold_diff(int *zone_diff, int *node_diff)
710 {
711 	int i;
712 	int changes = 0;
713 
714 	for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
715 		if (zone_diff[i]) {
716 			atomic_long_add(zone_diff[i], &vm_zone_stat[i]);
717 			changes++;
718 	}
719 
720 	for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++)
721 		if (node_diff[i]) {
722 			atomic_long_add(node_diff[i], &vm_node_stat[i]);
723 			changes++;
724 	}
725 	return changes;
726 }
727 #endif /* CONFIG_NUMA */
728 
729 /*
730  * Update the zone counters for the current cpu.
731  *
732  * Note that refresh_cpu_vm_stats strives to only access
733  * node local memory. The per cpu pagesets on remote zones are placed
734  * in the memory local to the processor using that pageset. So the
735  * loop over all zones will access a series of cachelines local to
736  * the processor.
737  *
738  * The call to zone_page_state_add updates the cachelines with the
739  * statistics in the remote zone struct as well as the global cachelines
740  * with the global counters. These could cause remote node cache line
741  * bouncing and will have to be only done when necessary.
742  *
743  * The function returns the number of global counters updated.
744  */
745 static int refresh_cpu_vm_stats(bool do_pagesets)
746 {
747 	struct pglist_data *pgdat;
748 	struct zone *zone;
749 	int i;
750 	int global_zone_diff[NR_VM_ZONE_STAT_ITEMS] = { 0, };
751 #ifdef CONFIG_NUMA
752 	int global_numa_diff[NR_VM_NUMA_STAT_ITEMS] = { 0, };
753 #endif
754 	int global_node_diff[NR_VM_NODE_STAT_ITEMS] = { 0, };
755 	int changes = 0;
756 
757 	for_each_populated_zone(zone) {
758 		struct per_cpu_pageset __percpu *p = zone->pageset;
759 
760 		for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++) {
761 			int v;
762 
763 			v = this_cpu_xchg(p->vm_stat_diff[i], 0);
764 			if (v) {
765 
766 				atomic_long_add(v, &zone->vm_stat[i]);
767 				global_zone_diff[i] += v;
768 #ifdef CONFIG_NUMA
769 				/* 3 seconds idle till flush */
770 				__this_cpu_write(p->expire, 3);
771 #endif
772 			}
773 		}
774 #ifdef CONFIG_NUMA
775 		for (i = 0; i < NR_VM_NUMA_STAT_ITEMS; i++) {
776 			int v;
777 
778 			v = this_cpu_xchg(p->vm_numa_stat_diff[i], 0);
779 			if (v) {
780 
781 				atomic_long_add(v, &zone->vm_numa_stat[i]);
782 				global_numa_diff[i] += v;
783 				__this_cpu_write(p->expire, 3);
784 			}
785 		}
786 
787 		if (do_pagesets) {
788 			cond_resched();
789 			/*
790 			 * Deal with draining the remote pageset of this
791 			 * processor
792 			 *
793 			 * Check if there are pages remaining in this pageset
794 			 * if not then there is nothing to expire.
795 			 */
796 			if (!__this_cpu_read(p->expire) ||
797 			       !__this_cpu_read(p->pcp.count))
798 				continue;
799 
800 			/*
801 			 * We never drain zones local to this processor.
802 			 */
803 			if (zone_to_nid(zone) == numa_node_id()) {
804 				__this_cpu_write(p->expire, 0);
805 				continue;
806 			}
807 
808 			if (__this_cpu_dec_return(p->expire))
809 				continue;
810 
811 			if (__this_cpu_read(p->pcp.count)) {
812 				drain_zone_pages(zone, this_cpu_ptr(&p->pcp));
813 				changes++;
814 			}
815 		}
816 #endif
817 	}
818 
819 	for_each_online_pgdat(pgdat) {
820 		struct per_cpu_nodestat __percpu *p = pgdat->per_cpu_nodestats;
821 
822 		for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++) {
823 			int v;
824 
825 			v = this_cpu_xchg(p->vm_node_stat_diff[i], 0);
826 			if (v) {
827 				atomic_long_add(v, &pgdat->vm_stat[i]);
828 				global_node_diff[i] += v;
829 			}
830 		}
831 	}
832 
833 #ifdef CONFIG_NUMA
834 	changes += fold_diff(global_zone_diff, global_numa_diff,
835 			     global_node_diff);
836 #else
837 	changes += fold_diff(global_zone_diff, global_node_diff);
838 #endif
839 	return changes;
840 }
841 
842 /*
843  * Fold the data for an offline cpu into the global array.
844  * There cannot be any access by the offline cpu and therefore
845  * synchronization is simplified.
846  */
847 void cpu_vm_stats_fold(int cpu)
848 {
849 	struct pglist_data *pgdat;
850 	struct zone *zone;
851 	int i;
852 	int global_zone_diff[NR_VM_ZONE_STAT_ITEMS] = { 0, };
853 #ifdef CONFIG_NUMA
854 	int global_numa_diff[NR_VM_NUMA_STAT_ITEMS] = { 0, };
855 #endif
856 	int global_node_diff[NR_VM_NODE_STAT_ITEMS] = { 0, };
857 
858 	for_each_populated_zone(zone) {
859 		struct per_cpu_pageset *p;
860 
861 		p = per_cpu_ptr(zone->pageset, cpu);
862 
863 		for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
864 			if (p->vm_stat_diff[i]) {
865 				int v;
866 
867 				v = p->vm_stat_diff[i];
868 				p->vm_stat_diff[i] = 0;
869 				atomic_long_add(v, &zone->vm_stat[i]);
870 				global_zone_diff[i] += v;
871 			}
872 
873 #ifdef CONFIG_NUMA
874 		for (i = 0; i < NR_VM_NUMA_STAT_ITEMS; i++)
875 			if (p->vm_numa_stat_diff[i]) {
876 				int v;
877 
878 				v = p->vm_numa_stat_diff[i];
879 				p->vm_numa_stat_diff[i] = 0;
880 				atomic_long_add(v, &zone->vm_numa_stat[i]);
881 				global_numa_diff[i] += v;
882 			}
883 #endif
884 	}
885 
886 	for_each_online_pgdat(pgdat) {
887 		struct per_cpu_nodestat *p;
888 
889 		p = per_cpu_ptr(pgdat->per_cpu_nodestats, cpu);
890 
891 		for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++)
892 			if (p->vm_node_stat_diff[i]) {
893 				int v;
894 
895 				v = p->vm_node_stat_diff[i];
896 				p->vm_node_stat_diff[i] = 0;
897 				atomic_long_add(v, &pgdat->vm_stat[i]);
898 				global_node_diff[i] += v;
899 			}
900 	}
901 
902 #ifdef CONFIG_NUMA
903 	fold_diff(global_zone_diff, global_numa_diff, global_node_diff);
904 #else
905 	fold_diff(global_zone_diff, global_node_diff);
906 #endif
907 }
908 
909 /*
910  * this is only called if !populated_zone(zone), which implies no other users of
911  * pset->vm_stat_diff[] exsist.
912  */
913 void drain_zonestat(struct zone *zone, struct per_cpu_pageset *pset)
914 {
915 	int i;
916 
917 	for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
918 		if (pset->vm_stat_diff[i]) {
919 			int v = pset->vm_stat_diff[i];
920 			pset->vm_stat_diff[i] = 0;
921 			atomic_long_add(v, &zone->vm_stat[i]);
922 			atomic_long_add(v, &vm_zone_stat[i]);
923 		}
924 
925 #ifdef CONFIG_NUMA
926 	for (i = 0; i < NR_VM_NUMA_STAT_ITEMS; i++)
927 		if (pset->vm_numa_stat_diff[i]) {
928 			int v = pset->vm_numa_stat_diff[i];
929 
930 			pset->vm_numa_stat_diff[i] = 0;
931 			atomic_long_add(v, &zone->vm_numa_stat[i]);
932 			atomic_long_add(v, &vm_numa_stat[i]);
933 		}
934 #endif
935 }
936 #endif
937 
938 #ifdef CONFIG_NUMA
939 void __inc_numa_state(struct zone *zone,
940 				 enum numa_stat_item item)
941 {
942 	struct per_cpu_pageset __percpu *pcp = zone->pageset;
943 	u16 __percpu *p = pcp->vm_numa_stat_diff + item;
944 	u16 v;
945 
946 	v = __this_cpu_inc_return(*p);
947 
948 	if (unlikely(v > NUMA_STATS_THRESHOLD)) {
949 		zone_numa_state_add(v, zone, item);
950 		__this_cpu_write(*p, 0);
951 	}
952 }
953 
954 /*
955  * Determine the per node value of a stat item. This function
956  * is called frequently in a NUMA machine, so try to be as
957  * frugal as possible.
958  */
959 unsigned long sum_zone_node_page_state(int node,
960 				 enum zone_stat_item item)
961 {
962 	struct zone *zones = NODE_DATA(node)->node_zones;
963 	int i;
964 	unsigned long count = 0;
965 
966 	for (i = 0; i < MAX_NR_ZONES; i++)
967 		count += zone_page_state(zones + i, item);
968 
969 	return count;
970 }
971 
972 /*
973  * Determine the per node value of a numa stat item. To avoid deviation,
974  * the per cpu stat number in vm_numa_stat_diff[] is also included.
975  */
976 unsigned long sum_zone_numa_state(int node,
977 				 enum numa_stat_item item)
978 {
979 	struct zone *zones = NODE_DATA(node)->node_zones;
980 	int i;
981 	unsigned long count = 0;
982 
983 	for (i = 0; i < MAX_NR_ZONES; i++)
984 		count += zone_numa_state_snapshot(zones + i, item);
985 
986 	return count;
987 }
988 
989 /*
990  * Determine the per node value of a stat item.
991  */
992 unsigned long node_page_state(struct pglist_data *pgdat,
993 				enum node_stat_item item)
994 {
995 	long x = atomic_long_read(&pgdat->vm_stat[item]);
996 #ifdef CONFIG_SMP
997 	if (x < 0)
998 		x = 0;
999 #endif
1000 	return x;
1001 }
1002 #endif
1003 
1004 #ifdef CONFIG_COMPACTION
1005 
1006 struct contig_page_info {
1007 	unsigned long free_pages;
1008 	unsigned long free_blocks_total;
1009 	unsigned long free_blocks_suitable;
1010 };
1011 
1012 /*
1013  * Calculate the number of free pages in a zone, how many contiguous
1014  * pages are free and how many are large enough to satisfy an allocation of
1015  * the target size. Note that this function makes no attempt to estimate
1016  * how many suitable free blocks there *might* be if MOVABLE pages were
1017  * migrated. Calculating that is possible, but expensive and can be
1018  * figured out from userspace
1019  */
1020 static void fill_contig_page_info(struct zone *zone,
1021 				unsigned int suitable_order,
1022 				struct contig_page_info *info)
1023 {
1024 	unsigned int order;
1025 
1026 	info->free_pages = 0;
1027 	info->free_blocks_total = 0;
1028 	info->free_blocks_suitable = 0;
1029 
1030 	for (order = 0; order < MAX_ORDER; order++) {
1031 		unsigned long blocks;
1032 
1033 		/* Count number of free blocks */
1034 		blocks = zone->free_area[order].nr_free;
1035 		info->free_blocks_total += blocks;
1036 
1037 		/* Count free base pages */
1038 		info->free_pages += blocks << order;
1039 
1040 		/* Count the suitable free blocks */
1041 		if (order >= suitable_order)
1042 			info->free_blocks_suitable += blocks <<
1043 						(order - suitable_order);
1044 	}
1045 }
1046 
1047 /*
1048  * A fragmentation index only makes sense if an allocation of a requested
1049  * size would fail. If that is true, the fragmentation index indicates
1050  * whether external fragmentation or a lack of memory was the problem.
1051  * The value can be used to determine if page reclaim or compaction
1052  * should be used
1053  */
1054 static int __fragmentation_index(unsigned int order, struct contig_page_info *info)
1055 {
1056 	unsigned long requested = 1UL << order;
1057 
1058 	if (WARN_ON_ONCE(order >= MAX_ORDER))
1059 		return 0;
1060 
1061 	if (!info->free_blocks_total)
1062 		return 0;
1063 
1064 	/* Fragmentation index only makes sense when a request would fail */
1065 	if (info->free_blocks_suitable)
1066 		return -1000;
1067 
1068 	/*
1069 	 * Index is between 0 and 1 so return within 3 decimal places
1070 	 *
1071 	 * 0 => allocation would fail due to lack of memory
1072 	 * 1 => allocation would fail due to fragmentation
1073 	 */
1074 	return 1000 - div_u64( (1000+(div_u64(info->free_pages * 1000ULL, requested))), info->free_blocks_total);
1075 }
1076 
1077 /* Same as __fragmentation index but allocs contig_page_info on stack */
1078 int fragmentation_index(struct zone *zone, unsigned int order)
1079 {
1080 	struct contig_page_info info;
1081 
1082 	fill_contig_page_info(zone, order, &info);
1083 	return __fragmentation_index(order, &info);
1084 }
1085 #endif
1086 
1087 #if defined(CONFIG_PROC_FS) || defined(CONFIG_SYSFS) || \
1088     defined(CONFIG_NUMA) || defined(CONFIG_MEMCG)
1089 #ifdef CONFIG_ZONE_DMA
1090 #define TEXT_FOR_DMA(xx) xx "_dma",
1091 #else
1092 #define TEXT_FOR_DMA(xx)
1093 #endif
1094 
1095 #ifdef CONFIG_ZONE_DMA32
1096 #define TEXT_FOR_DMA32(xx) xx "_dma32",
1097 #else
1098 #define TEXT_FOR_DMA32(xx)
1099 #endif
1100 
1101 #ifdef CONFIG_HIGHMEM
1102 #define TEXT_FOR_HIGHMEM(xx) xx "_high",
1103 #else
1104 #define TEXT_FOR_HIGHMEM(xx)
1105 #endif
1106 
1107 #define TEXTS_FOR_ZONES(xx) TEXT_FOR_DMA(xx) TEXT_FOR_DMA32(xx) xx "_normal", \
1108 					TEXT_FOR_HIGHMEM(xx) xx "_movable",
1109 
1110 const char * const vmstat_text[] = {
1111 	/* enum zone_stat_item countes */
1112 	"nr_free_pages",
1113 	"nr_zone_inactive_anon",
1114 	"nr_zone_active_anon",
1115 	"nr_zone_inactive_file",
1116 	"nr_zone_active_file",
1117 	"nr_zone_unevictable",
1118 	"nr_zone_write_pending",
1119 	"nr_mlock",
1120 	"nr_page_table_pages",
1121 	"nr_kernel_stack",
1122 	"nr_bounce",
1123 #if IS_ENABLED(CONFIG_ZSMALLOC)
1124 	"nr_zspages",
1125 #endif
1126 	"nr_free_cma",
1127 
1128 	/* enum numa_stat_item counters */
1129 #ifdef CONFIG_NUMA
1130 	"numa_hit",
1131 	"numa_miss",
1132 	"numa_foreign",
1133 	"numa_interleave",
1134 	"numa_local",
1135 	"numa_other",
1136 #endif
1137 
1138 	/* enum node_stat_item counters */
1139 	"nr_inactive_anon",
1140 	"nr_active_anon",
1141 	"nr_inactive_file",
1142 	"nr_active_file",
1143 	"nr_unevictable",
1144 	"nr_slab_reclaimable",
1145 	"nr_slab_unreclaimable",
1146 	"nr_isolated_anon",
1147 	"nr_isolated_file",
1148 	"workingset_nodes",
1149 	"workingset_refault",
1150 	"workingset_activate",
1151 	"workingset_restore",
1152 	"workingset_nodereclaim",
1153 	"nr_anon_pages",
1154 	"nr_mapped",
1155 	"nr_file_pages",
1156 	"nr_dirty",
1157 	"nr_writeback",
1158 	"nr_writeback_temp",
1159 	"nr_shmem",
1160 	"nr_shmem_hugepages",
1161 	"nr_shmem_pmdmapped",
1162 	"nr_file_hugepages",
1163 	"nr_file_pmdmapped",
1164 	"nr_anon_transparent_hugepages",
1165 	"nr_unstable",
1166 	"nr_vmscan_write",
1167 	"nr_vmscan_immediate_reclaim",
1168 	"nr_dirtied",
1169 	"nr_written",
1170 	"nr_kernel_misc_reclaimable",
1171 
1172 	/* enum writeback_stat_item counters */
1173 	"nr_dirty_threshold",
1174 	"nr_dirty_background_threshold",
1175 
1176 #if defined(CONFIG_VM_EVENT_COUNTERS) || defined(CONFIG_MEMCG)
1177 	/* enum vm_event_item counters */
1178 	"pgpgin",
1179 	"pgpgout",
1180 	"pswpin",
1181 	"pswpout",
1182 
1183 	TEXTS_FOR_ZONES("pgalloc")
1184 	TEXTS_FOR_ZONES("allocstall")
1185 	TEXTS_FOR_ZONES("pgskip")
1186 
1187 	"pgfree",
1188 	"pgactivate",
1189 	"pgdeactivate",
1190 	"pglazyfree",
1191 
1192 	"pgfault",
1193 	"pgmajfault",
1194 	"pglazyfreed",
1195 
1196 	"pgrefill",
1197 	"pgsteal_kswapd",
1198 	"pgsteal_direct",
1199 	"pgscan_kswapd",
1200 	"pgscan_direct",
1201 	"pgscan_direct_throttle",
1202 
1203 #ifdef CONFIG_NUMA
1204 	"zone_reclaim_failed",
1205 #endif
1206 	"pginodesteal",
1207 	"slabs_scanned",
1208 	"kswapd_inodesteal",
1209 	"kswapd_low_wmark_hit_quickly",
1210 	"kswapd_high_wmark_hit_quickly",
1211 	"pageoutrun",
1212 
1213 	"pgrotated",
1214 
1215 	"drop_pagecache",
1216 	"drop_slab",
1217 	"oom_kill",
1218 
1219 #ifdef CONFIG_NUMA_BALANCING
1220 	"numa_pte_updates",
1221 	"numa_huge_pte_updates",
1222 	"numa_hint_faults",
1223 	"numa_hint_faults_local",
1224 	"numa_pages_migrated",
1225 #endif
1226 #ifdef CONFIG_MIGRATION
1227 	"pgmigrate_success",
1228 	"pgmigrate_fail",
1229 #endif
1230 #ifdef CONFIG_COMPACTION
1231 	"compact_migrate_scanned",
1232 	"compact_free_scanned",
1233 	"compact_isolated",
1234 	"compact_stall",
1235 	"compact_fail",
1236 	"compact_success",
1237 	"compact_daemon_wake",
1238 	"compact_daemon_migrate_scanned",
1239 	"compact_daemon_free_scanned",
1240 #endif
1241 
1242 #ifdef CONFIG_HUGETLB_PAGE
1243 	"htlb_buddy_alloc_success",
1244 	"htlb_buddy_alloc_fail",
1245 #endif
1246 	"unevictable_pgs_culled",
1247 	"unevictable_pgs_scanned",
1248 	"unevictable_pgs_rescued",
1249 	"unevictable_pgs_mlocked",
1250 	"unevictable_pgs_munlocked",
1251 	"unevictable_pgs_cleared",
1252 	"unevictable_pgs_stranded",
1253 
1254 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
1255 	"thp_fault_alloc",
1256 	"thp_fault_fallback",
1257 	"thp_collapse_alloc",
1258 	"thp_collapse_alloc_failed",
1259 	"thp_file_alloc",
1260 	"thp_file_mapped",
1261 	"thp_split_page",
1262 	"thp_split_page_failed",
1263 	"thp_deferred_split_page",
1264 	"thp_split_pmd",
1265 #ifdef CONFIG_HAVE_ARCH_TRANSPARENT_HUGEPAGE_PUD
1266 	"thp_split_pud",
1267 #endif
1268 	"thp_zero_page_alloc",
1269 	"thp_zero_page_alloc_failed",
1270 	"thp_swpout",
1271 	"thp_swpout_fallback",
1272 #endif
1273 #ifdef CONFIG_MEMORY_BALLOON
1274 	"balloon_inflate",
1275 	"balloon_deflate",
1276 #ifdef CONFIG_BALLOON_COMPACTION
1277 	"balloon_migrate",
1278 #endif
1279 #endif /* CONFIG_MEMORY_BALLOON */
1280 #ifdef CONFIG_DEBUG_TLBFLUSH
1281 	"nr_tlb_remote_flush",
1282 	"nr_tlb_remote_flush_received",
1283 	"nr_tlb_local_flush_all",
1284 	"nr_tlb_local_flush_one",
1285 #endif /* CONFIG_DEBUG_TLBFLUSH */
1286 
1287 #ifdef CONFIG_DEBUG_VM_VMACACHE
1288 	"vmacache_find_calls",
1289 	"vmacache_find_hits",
1290 #endif
1291 #ifdef CONFIG_SWAP
1292 	"swap_ra",
1293 	"swap_ra_hit",
1294 #endif
1295 #endif /* CONFIG_VM_EVENT_COUNTERS || CONFIG_MEMCG */
1296 };
1297 #endif /* CONFIG_PROC_FS || CONFIG_SYSFS || CONFIG_NUMA || CONFIG_MEMCG */
1298 
1299 #if (defined(CONFIG_DEBUG_FS) && defined(CONFIG_COMPACTION)) || \
1300      defined(CONFIG_PROC_FS)
1301 static void *frag_start(struct seq_file *m, loff_t *pos)
1302 {
1303 	pg_data_t *pgdat;
1304 	loff_t node = *pos;
1305 
1306 	for (pgdat = first_online_pgdat();
1307 	     pgdat && node;
1308 	     pgdat = next_online_pgdat(pgdat))
1309 		--node;
1310 
1311 	return pgdat;
1312 }
1313 
1314 static void *frag_next(struct seq_file *m, void *arg, loff_t *pos)
1315 {
1316 	pg_data_t *pgdat = (pg_data_t *)arg;
1317 
1318 	(*pos)++;
1319 	return next_online_pgdat(pgdat);
1320 }
1321 
1322 static void frag_stop(struct seq_file *m, void *arg)
1323 {
1324 }
1325 
1326 /*
1327  * Walk zones in a node and print using a callback.
1328  * If @assert_populated is true, only use callback for zones that are populated.
1329  */
1330 static void walk_zones_in_node(struct seq_file *m, pg_data_t *pgdat,
1331 		bool assert_populated, bool nolock,
1332 		void (*print)(struct seq_file *m, pg_data_t *, struct zone *))
1333 {
1334 	struct zone *zone;
1335 	struct zone *node_zones = pgdat->node_zones;
1336 	unsigned long flags;
1337 
1338 	for (zone = node_zones; zone - node_zones < MAX_NR_ZONES; ++zone) {
1339 		if (assert_populated && !populated_zone(zone))
1340 			continue;
1341 
1342 		if (!nolock)
1343 			spin_lock_irqsave(&zone->lock, flags);
1344 		print(m, pgdat, zone);
1345 		if (!nolock)
1346 			spin_unlock_irqrestore(&zone->lock, flags);
1347 	}
1348 }
1349 #endif
1350 
1351 #ifdef CONFIG_PROC_FS
1352 static void frag_show_print(struct seq_file *m, pg_data_t *pgdat,
1353 						struct zone *zone)
1354 {
1355 	int order;
1356 
1357 	seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
1358 	for (order = 0; order < MAX_ORDER; ++order)
1359 		seq_printf(m, "%6lu ", zone->free_area[order].nr_free);
1360 	seq_putc(m, '\n');
1361 }
1362 
1363 /*
1364  * This walks the free areas for each zone.
1365  */
1366 static int frag_show(struct seq_file *m, void *arg)
1367 {
1368 	pg_data_t *pgdat = (pg_data_t *)arg;
1369 	walk_zones_in_node(m, pgdat, true, false, frag_show_print);
1370 	return 0;
1371 }
1372 
1373 static void pagetypeinfo_showfree_print(struct seq_file *m,
1374 					pg_data_t *pgdat, struct zone *zone)
1375 {
1376 	int order, mtype;
1377 
1378 	for (mtype = 0; mtype < MIGRATE_TYPES; mtype++) {
1379 		seq_printf(m, "Node %4d, zone %8s, type %12s ",
1380 					pgdat->node_id,
1381 					zone->name,
1382 					migratetype_names[mtype]);
1383 		for (order = 0; order < MAX_ORDER; ++order) {
1384 			unsigned long freecount = 0;
1385 			struct free_area *area;
1386 			struct list_head *curr;
1387 			bool overflow = false;
1388 
1389 			area = &(zone->free_area[order]);
1390 
1391 			list_for_each(curr, &area->free_list[mtype]) {
1392 				/*
1393 				 * Cap the free_list iteration because it might
1394 				 * be really large and we are under a spinlock
1395 				 * so a long time spent here could trigger a
1396 				 * hard lockup detector. Anyway this is a
1397 				 * debugging tool so knowing there is a handful
1398 				 * of pages of this order should be more than
1399 				 * sufficient.
1400 				 */
1401 				if (++freecount >= 100000) {
1402 					overflow = true;
1403 					break;
1404 				}
1405 			}
1406 			seq_printf(m, "%s%6lu ", overflow ? ">" : "", freecount);
1407 			spin_unlock_irq(&zone->lock);
1408 			cond_resched();
1409 			spin_lock_irq(&zone->lock);
1410 		}
1411 		seq_putc(m, '\n');
1412 	}
1413 }
1414 
1415 /* Print out the free pages at each order for each migatetype */
1416 static int pagetypeinfo_showfree(struct seq_file *m, void *arg)
1417 {
1418 	int order;
1419 	pg_data_t *pgdat = (pg_data_t *)arg;
1420 
1421 	/* Print header */
1422 	seq_printf(m, "%-43s ", "Free pages count per migrate type at order");
1423 	for (order = 0; order < MAX_ORDER; ++order)
1424 		seq_printf(m, "%6d ", order);
1425 	seq_putc(m, '\n');
1426 
1427 	walk_zones_in_node(m, pgdat, true, false, pagetypeinfo_showfree_print);
1428 
1429 	return 0;
1430 }
1431 
1432 static void pagetypeinfo_showblockcount_print(struct seq_file *m,
1433 					pg_data_t *pgdat, struct zone *zone)
1434 {
1435 	int mtype;
1436 	unsigned long pfn;
1437 	unsigned long start_pfn = zone->zone_start_pfn;
1438 	unsigned long end_pfn = zone_end_pfn(zone);
1439 	unsigned long count[MIGRATE_TYPES] = { 0, };
1440 
1441 	for (pfn = start_pfn; pfn < end_pfn; pfn += pageblock_nr_pages) {
1442 		struct page *page;
1443 
1444 		page = pfn_to_online_page(pfn);
1445 		if (!page)
1446 			continue;
1447 
1448 		/* Watch for unexpected holes punched in the memmap */
1449 		if (!memmap_valid_within(pfn, page, zone))
1450 			continue;
1451 
1452 		if (page_zone(page) != zone)
1453 			continue;
1454 
1455 		mtype = get_pageblock_migratetype(page);
1456 
1457 		if (mtype < MIGRATE_TYPES)
1458 			count[mtype]++;
1459 	}
1460 
1461 	/* Print counts */
1462 	seq_printf(m, "Node %d, zone %8s ", pgdat->node_id, zone->name);
1463 	for (mtype = 0; mtype < MIGRATE_TYPES; mtype++)
1464 		seq_printf(m, "%12lu ", count[mtype]);
1465 	seq_putc(m, '\n');
1466 }
1467 
1468 /* Print out the number of pageblocks for each migratetype */
1469 static int pagetypeinfo_showblockcount(struct seq_file *m, void *arg)
1470 {
1471 	int mtype;
1472 	pg_data_t *pgdat = (pg_data_t *)arg;
1473 
1474 	seq_printf(m, "\n%-23s", "Number of blocks type ");
1475 	for (mtype = 0; mtype < MIGRATE_TYPES; mtype++)
1476 		seq_printf(m, "%12s ", migratetype_names[mtype]);
1477 	seq_putc(m, '\n');
1478 	walk_zones_in_node(m, pgdat, true, false,
1479 		pagetypeinfo_showblockcount_print);
1480 
1481 	return 0;
1482 }
1483 
1484 /*
1485  * Print out the number of pageblocks for each migratetype that contain pages
1486  * of other types. This gives an indication of how well fallbacks are being
1487  * contained by rmqueue_fallback(). It requires information from PAGE_OWNER
1488  * to determine what is going on
1489  */
1490 static void pagetypeinfo_showmixedcount(struct seq_file *m, pg_data_t *pgdat)
1491 {
1492 #ifdef CONFIG_PAGE_OWNER
1493 	int mtype;
1494 
1495 	if (!static_branch_unlikely(&page_owner_inited))
1496 		return;
1497 
1498 	drain_all_pages(NULL);
1499 
1500 	seq_printf(m, "\n%-23s", "Number of mixed blocks ");
1501 	for (mtype = 0; mtype < MIGRATE_TYPES; mtype++)
1502 		seq_printf(m, "%12s ", migratetype_names[mtype]);
1503 	seq_putc(m, '\n');
1504 
1505 	walk_zones_in_node(m, pgdat, true, true,
1506 		pagetypeinfo_showmixedcount_print);
1507 #endif /* CONFIG_PAGE_OWNER */
1508 }
1509 
1510 /*
1511  * This prints out statistics in relation to grouping pages by mobility.
1512  * It is expensive to collect so do not constantly read the file.
1513  */
1514 static int pagetypeinfo_show(struct seq_file *m, void *arg)
1515 {
1516 	pg_data_t *pgdat = (pg_data_t *)arg;
1517 
1518 	/* check memoryless node */
1519 	if (!node_state(pgdat->node_id, N_MEMORY))
1520 		return 0;
1521 
1522 	seq_printf(m, "Page block order: %d\n", pageblock_order);
1523 	seq_printf(m, "Pages per block:  %lu\n", pageblock_nr_pages);
1524 	seq_putc(m, '\n');
1525 	pagetypeinfo_showfree(m, pgdat);
1526 	pagetypeinfo_showblockcount(m, pgdat);
1527 	pagetypeinfo_showmixedcount(m, pgdat);
1528 
1529 	return 0;
1530 }
1531 
1532 static const struct seq_operations fragmentation_op = {
1533 	.start	= frag_start,
1534 	.next	= frag_next,
1535 	.stop	= frag_stop,
1536 	.show	= frag_show,
1537 };
1538 
1539 static const struct seq_operations pagetypeinfo_op = {
1540 	.start	= frag_start,
1541 	.next	= frag_next,
1542 	.stop	= frag_stop,
1543 	.show	= pagetypeinfo_show,
1544 };
1545 
1546 static bool is_zone_first_populated(pg_data_t *pgdat, struct zone *zone)
1547 {
1548 	int zid;
1549 
1550 	for (zid = 0; zid < MAX_NR_ZONES; zid++) {
1551 		struct zone *compare = &pgdat->node_zones[zid];
1552 
1553 		if (populated_zone(compare))
1554 			return zone == compare;
1555 	}
1556 
1557 	return false;
1558 }
1559 
1560 static void zoneinfo_show_print(struct seq_file *m, pg_data_t *pgdat,
1561 							struct zone *zone)
1562 {
1563 	int i;
1564 	seq_printf(m, "Node %d, zone %8s", pgdat->node_id, zone->name);
1565 	if (is_zone_first_populated(pgdat, zone)) {
1566 		seq_printf(m, "\n  per-node stats");
1567 		for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++) {
1568 			seq_printf(m, "\n      %-12s %lu", node_stat_name(i),
1569 				   node_page_state(pgdat, i));
1570 		}
1571 	}
1572 	seq_printf(m,
1573 		   "\n  pages free     %lu"
1574 		   "\n        min      %lu"
1575 		   "\n        low      %lu"
1576 		   "\n        high     %lu"
1577 		   "\n        spanned  %lu"
1578 		   "\n        present  %lu"
1579 		   "\n        managed  %lu",
1580 		   zone_page_state(zone, NR_FREE_PAGES),
1581 		   min_wmark_pages(zone),
1582 		   low_wmark_pages(zone),
1583 		   high_wmark_pages(zone),
1584 		   zone->spanned_pages,
1585 		   zone->present_pages,
1586 		   zone_managed_pages(zone));
1587 
1588 	seq_printf(m,
1589 		   "\n        protection: (%ld",
1590 		   zone->lowmem_reserve[0]);
1591 	for (i = 1; i < ARRAY_SIZE(zone->lowmem_reserve); i++)
1592 		seq_printf(m, ", %ld", zone->lowmem_reserve[i]);
1593 	seq_putc(m, ')');
1594 
1595 	/* If unpopulated, no other information is useful */
1596 	if (!populated_zone(zone)) {
1597 		seq_putc(m, '\n');
1598 		return;
1599 	}
1600 
1601 	for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
1602 		seq_printf(m, "\n      %-12s %lu", zone_stat_name(i),
1603 			   zone_page_state(zone, i));
1604 
1605 #ifdef CONFIG_NUMA
1606 	for (i = 0; i < NR_VM_NUMA_STAT_ITEMS; i++)
1607 		seq_printf(m, "\n      %-12s %lu", numa_stat_name(i),
1608 			   zone_numa_state_snapshot(zone, i));
1609 #endif
1610 
1611 	seq_printf(m, "\n  pagesets");
1612 	for_each_online_cpu(i) {
1613 		struct per_cpu_pageset *pageset;
1614 
1615 		pageset = per_cpu_ptr(zone->pageset, i);
1616 		seq_printf(m,
1617 			   "\n    cpu: %i"
1618 			   "\n              count: %i"
1619 			   "\n              high:  %i"
1620 			   "\n              batch: %i",
1621 			   i,
1622 			   pageset->pcp.count,
1623 			   pageset->pcp.high,
1624 			   pageset->pcp.batch);
1625 #ifdef CONFIG_SMP
1626 		seq_printf(m, "\n  vm stats threshold: %d",
1627 				pageset->stat_threshold);
1628 #endif
1629 	}
1630 	seq_printf(m,
1631 		   "\n  node_unreclaimable:  %u"
1632 		   "\n  start_pfn:           %lu",
1633 		   pgdat->kswapd_failures >= MAX_RECLAIM_RETRIES,
1634 		   zone->zone_start_pfn);
1635 	seq_putc(m, '\n');
1636 }
1637 
1638 /*
1639  * Output information about zones in @pgdat.  All zones are printed regardless
1640  * of whether they are populated or not: lowmem_reserve_ratio operates on the
1641  * set of all zones and userspace would not be aware of such zones if they are
1642  * suppressed here (zoneinfo displays the effect of lowmem_reserve_ratio).
1643  */
1644 static int zoneinfo_show(struct seq_file *m, void *arg)
1645 {
1646 	pg_data_t *pgdat = (pg_data_t *)arg;
1647 	walk_zones_in_node(m, pgdat, false, false, zoneinfo_show_print);
1648 	return 0;
1649 }
1650 
1651 static const struct seq_operations zoneinfo_op = {
1652 	.start	= frag_start, /* iterate over all zones. The same as in
1653 			       * fragmentation. */
1654 	.next	= frag_next,
1655 	.stop	= frag_stop,
1656 	.show	= zoneinfo_show,
1657 };
1658 
1659 #define NR_VMSTAT_ITEMS (NR_VM_ZONE_STAT_ITEMS + \
1660 			 NR_VM_NUMA_STAT_ITEMS + \
1661 			 NR_VM_NODE_STAT_ITEMS + \
1662 			 NR_VM_WRITEBACK_STAT_ITEMS + \
1663 			 (IS_ENABLED(CONFIG_VM_EVENT_COUNTERS) ? \
1664 			  NR_VM_EVENT_ITEMS : 0))
1665 
1666 static void *vmstat_start(struct seq_file *m, loff_t *pos)
1667 {
1668 	unsigned long *v;
1669 	int i;
1670 
1671 	if (*pos >= NR_VMSTAT_ITEMS)
1672 		return NULL;
1673 
1674 	BUILD_BUG_ON(ARRAY_SIZE(vmstat_text) < NR_VMSTAT_ITEMS);
1675 	v = kmalloc_array(NR_VMSTAT_ITEMS, sizeof(unsigned long), GFP_KERNEL);
1676 	m->private = v;
1677 	if (!v)
1678 		return ERR_PTR(-ENOMEM);
1679 	for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++)
1680 		v[i] = global_zone_page_state(i);
1681 	v += NR_VM_ZONE_STAT_ITEMS;
1682 
1683 #ifdef CONFIG_NUMA
1684 	for (i = 0; i < NR_VM_NUMA_STAT_ITEMS; i++)
1685 		v[i] = global_numa_state(i);
1686 	v += NR_VM_NUMA_STAT_ITEMS;
1687 #endif
1688 
1689 	for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++)
1690 		v[i] = global_node_page_state(i);
1691 	v += NR_VM_NODE_STAT_ITEMS;
1692 
1693 	global_dirty_limits(v + NR_DIRTY_BG_THRESHOLD,
1694 			    v + NR_DIRTY_THRESHOLD);
1695 	v += NR_VM_WRITEBACK_STAT_ITEMS;
1696 
1697 #ifdef CONFIG_VM_EVENT_COUNTERS
1698 	all_vm_events(v);
1699 	v[PGPGIN] /= 2;		/* sectors -> kbytes */
1700 	v[PGPGOUT] /= 2;
1701 #endif
1702 	return (unsigned long *)m->private + *pos;
1703 }
1704 
1705 static void *vmstat_next(struct seq_file *m, void *arg, loff_t *pos)
1706 {
1707 	(*pos)++;
1708 	if (*pos >= NR_VMSTAT_ITEMS)
1709 		return NULL;
1710 	return (unsigned long *)m->private + *pos;
1711 }
1712 
1713 static int vmstat_show(struct seq_file *m, void *arg)
1714 {
1715 	unsigned long *l = arg;
1716 	unsigned long off = l - (unsigned long *)m->private;
1717 
1718 	seq_puts(m, vmstat_text[off]);
1719 	seq_put_decimal_ull(m, " ", *l);
1720 	seq_putc(m, '\n');
1721 	return 0;
1722 }
1723 
1724 static void vmstat_stop(struct seq_file *m, void *arg)
1725 {
1726 	kfree(m->private);
1727 	m->private = NULL;
1728 }
1729 
1730 static const struct seq_operations vmstat_op = {
1731 	.start	= vmstat_start,
1732 	.next	= vmstat_next,
1733 	.stop	= vmstat_stop,
1734 	.show	= vmstat_show,
1735 };
1736 #endif /* CONFIG_PROC_FS */
1737 
1738 #ifdef CONFIG_SMP
1739 static DEFINE_PER_CPU(struct delayed_work, vmstat_work);
1740 int sysctl_stat_interval __read_mostly = HZ;
1741 
1742 #ifdef CONFIG_PROC_FS
1743 static void refresh_vm_stats(struct work_struct *work)
1744 {
1745 	refresh_cpu_vm_stats(true);
1746 }
1747 
1748 int vmstat_refresh(struct ctl_table *table, int write,
1749 		   void __user *buffer, size_t *lenp, loff_t *ppos)
1750 {
1751 	long val;
1752 	int err;
1753 	int i;
1754 
1755 	/*
1756 	 * The regular update, every sysctl_stat_interval, may come later
1757 	 * than expected: leaving a significant amount in per_cpu buckets.
1758 	 * This is particularly misleading when checking a quantity of HUGE
1759 	 * pages, immediately after running a test.  /proc/sys/vm/stat_refresh,
1760 	 * which can equally be echo'ed to or cat'ted from (by root),
1761 	 * can be used to update the stats just before reading them.
1762 	 *
1763 	 * Oh, and since global_zone_page_state() etc. are so careful to hide
1764 	 * transiently negative values, report an error here if any of
1765 	 * the stats is negative, so we know to go looking for imbalance.
1766 	 */
1767 	err = schedule_on_each_cpu(refresh_vm_stats);
1768 	if (err)
1769 		return err;
1770 	for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++) {
1771 		val = atomic_long_read(&vm_zone_stat[i]);
1772 		if (val < 0) {
1773 			pr_warn("%s: %s %ld\n",
1774 				__func__, zone_stat_name(i), val);
1775 			err = -EINVAL;
1776 		}
1777 	}
1778 #ifdef CONFIG_NUMA
1779 	for (i = 0; i < NR_VM_NUMA_STAT_ITEMS; i++) {
1780 		val = atomic_long_read(&vm_numa_stat[i]);
1781 		if (val < 0) {
1782 			pr_warn("%s: %s %ld\n",
1783 				__func__, numa_stat_name(i), val);
1784 			err = -EINVAL;
1785 		}
1786 	}
1787 #endif
1788 	if (err)
1789 		return err;
1790 	if (write)
1791 		*ppos += *lenp;
1792 	else
1793 		*lenp = 0;
1794 	return 0;
1795 }
1796 #endif /* CONFIG_PROC_FS */
1797 
1798 static void vmstat_update(struct work_struct *w)
1799 {
1800 	if (refresh_cpu_vm_stats(true)) {
1801 		/*
1802 		 * Counters were updated so we expect more updates
1803 		 * to occur in the future. Keep on running the
1804 		 * update worker thread.
1805 		 */
1806 		queue_delayed_work_on(smp_processor_id(), mm_percpu_wq,
1807 				this_cpu_ptr(&vmstat_work),
1808 				round_jiffies_relative(sysctl_stat_interval));
1809 	}
1810 }
1811 
1812 /*
1813  * Switch off vmstat processing and then fold all the remaining differentials
1814  * until the diffs stay at zero. The function is used by NOHZ and can only be
1815  * invoked when tick processing is not active.
1816  */
1817 /*
1818  * Check if the diffs for a certain cpu indicate that
1819  * an update is needed.
1820  */
1821 static bool need_update(int cpu)
1822 {
1823 	struct zone *zone;
1824 
1825 	for_each_populated_zone(zone) {
1826 		struct per_cpu_pageset *p = per_cpu_ptr(zone->pageset, cpu);
1827 
1828 		BUILD_BUG_ON(sizeof(p->vm_stat_diff[0]) != 1);
1829 #ifdef CONFIG_NUMA
1830 		BUILD_BUG_ON(sizeof(p->vm_numa_stat_diff[0]) != 2);
1831 #endif
1832 
1833 		/*
1834 		 * The fast way of checking if there are any vmstat diffs.
1835 		 */
1836 		if (memchr_inv(p->vm_stat_diff, 0, NR_VM_ZONE_STAT_ITEMS *
1837 			       sizeof(p->vm_stat_diff[0])))
1838 			return true;
1839 #ifdef CONFIG_NUMA
1840 		if (memchr_inv(p->vm_numa_stat_diff, 0, NR_VM_NUMA_STAT_ITEMS *
1841 			       sizeof(p->vm_numa_stat_diff[0])))
1842 			return true;
1843 #endif
1844 	}
1845 	return false;
1846 }
1847 
1848 /*
1849  * Switch off vmstat processing and then fold all the remaining differentials
1850  * until the diffs stay at zero. The function is used by NOHZ and can only be
1851  * invoked when tick processing is not active.
1852  */
1853 void quiet_vmstat(void)
1854 {
1855 	if (system_state != SYSTEM_RUNNING)
1856 		return;
1857 
1858 	if (!delayed_work_pending(this_cpu_ptr(&vmstat_work)))
1859 		return;
1860 
1861 	if (!need_update(smp_processor_id()))
1862 		return;
1863 
1864 	/*
1865 	 * Just refresh counters and do not care about the pending delayed
1866 	 * vmstat_update. It doesn't fire that often to matter and canceling
1867 	 * it would be too expensive from this path.
1868 	 * vmstat_shepherd will take care about that for us.
1869 	 */
1870 	refresh_cpu_vm_stats(false);
1871 }
1872 
1873 /*
1874  * Shepherd worker thread that checks the
1875  * differentials of processors that have their worker
1876  * threads for vm statistics updates disabled because of
1877  * inactivity.
1878  */
1879 static void vmstat_shepherd(struct work_struct *w);
1880 
1881 static DECLARE_DEFERRABLE_WORK(shepherd, vmstat_shepherd);
1882 
1883 static void vmstat_shepherd(struct work_struct *w)
1884 {
1885 	int cpu;
1886 
1887 	get_online_cpus();
1888 	/* Check processors whose vmstat worker threads have been disabled */
1889 	for_each_online_cpu(cpu) {
1890 		struct delayed_work *dw = &per_cpu(vmstat_work, cpu);
1891 
1892 		if (!delayed_work_pending(dw) && need_update(cpu))
1893 			queue_delayed_work_on(cpu, mm_percpu_wq, dw, 0);
1894 	}
1895 	put_online_cpus();
1896 
1897 	schedule_delayed_work(&shepherd,
1898 		round_jiffies_relative(sysctl_stat_interval));
1899 }
1900 
1901 static void __init start_shepherd_timer(void)
1902 {
1903 	int cpu;
1904 
1905 	for_each_possible_cpu(cpu)
1906 		INIT_DEFERRABLE_WORK(per_cpu_ptr(&vmstat_work, cpu),
1907 			vmstat_update);
1908 
1909 	schedule_delayed_work(&shepherd,
1910 		round_jiffies_relative(sysctl_stat_interval));
1911 }
1912 
1913 static void __init init_cpu_node_state(void)
1914 {
1915 	int node;
1916 
1917 	for_each_online_node(node) {
1918 		if (cpumask_weight(cpumask_of_node(node)) > 0)
1919 			node_set_state(node, N_CPU);
1920 	}
1921 }
1922 
1923 static int vmstat_cpu_online(unsigned int cpu)
1924 {
1925 	refresh_zone_stat_thresholds();
1926 	node_set_state(cpu_to_node(cpu), N_CPU);
1927 	return 0;
1928 }
1929 
1930 static int vmstat_cpu_down_prep(unsigned int cpu)
1931 {
1932 	cancel_delayed_work_sync(&per_cpu(vmstat_work, cpu));
1933 	return 0;
1934 }
1935 
1936 static int vmstat_cpu_dead(unsigned int cpu)
1937 {
1938 	const struct cpumask *node_cpus;
1939 	int node;
1940 
1941 	node = cpu_to_node(cpu);
1942 
1943 	refresh_zone_stat_thresholds();
1944 	node_cpus = cpumask_of_node(node);
1945 	if (cpumask_weight(node_cpus) > 0)
1946 		return 0;
1947 
1948 	node_clear_state(node, N_CPU);
1949 	return 0;
1950 }
1951 
1952 #endif
1953 
1954 struct workqueue_struct *mm_percpu_wq;
1955 
1956 void __init init_mm_internals(void)
1957 {
1958 	int ret __maybe_unused;
1959 
1960 	mm_percpu_wq = alloc_workqueue("mm_percpu_wq", WQ_MEM_RECLAIM, 0);
1961 
1962 #ifdef CONFIG_SMP
1963 	ret = cpuhp_setup_state_nocalls(CPUHP_MM_VMSTAT_DEAD, "mm/vmstat:dead",
1964 					NULL, vmstat_cpu_dead);
1965 	if (ret < 0)
1966 		pr_err("vmstat: failed to register 'dead' hotplug state\n");
1967 
1968 	ret = cpuhp_setup_state_nocalls(CPUHP_AP_ONLINE_DYN, "mm/vmstat:online",
1969 					vmstat_cpu_online,
1970 					vmstat_cpu_down_prep);
1971 	if (ret < 0)
1972 		pr_err("vmstat: failed to register 'online' hotplug state\n");
1973 
1974 	get_online_cpus();
1975 	init_cpu_node_state();
1976 	put_online_cpus();
1977 
1978 	start_shepherd_timer();
1979 #endif
1980 #ifdef CONFIG_PROC_FS
1981 	proc_create_seq("buddyinfo", 0444, NULL, &fragmentation_op);
1982 	proc_create_seq("pagetypeinfo", 0400, NULL, &pagetypeinfo_op);
1983 	proc_create_seq("vmstat", 0444, NULL, &vmstat_op);
1984 	proc_create_seq("zoneinfo", 0444, NULL, &zoneinfo_op);
1985 #endif
1986 }
1987 
1988 #if defined(CONFIG_DEBUG_FS) && defined(CONFIG_COMPACTION)
1989 
1990 /*
1991  * Return an index indicating how much of the available free memory is
1992  * unusable for an allocation of the requested size.
1993  */
1994 static int unusable_free_index(unsigned int order,
1995 				struct contig_page_info *info)
1996 {
1997 	/* No free memory is interpreted as all free memory is unusable */
1998 	if (info->free_pages == 0)
1999 		return 1000;
2000 
2001 	/*
2002 	 * Index should be a value between 0 and 1. Return a value to 3
2003 	 * decimal places.
2004 	 *
2005 	 * 0 => no fragmentation
2006 	 * 1 => high fragmentation
2007 	 */
2008 	return div_u64((info->free_pages - (info->free_blocks_suitable << order)) * 1000ULL, info->free_pages);
2009 
2010 }
2011 
2012 static void unusable_show_print(struct seq_file *m,
2013 					pg_data_t *pgdat, struct zone *zone)
2014 {
2015 	unsigned int order;
2016 	int index;
2017 	struct contig_page_info info;
2018 
2019 	seq_printf(m, "Node %d, zone %8s ",
2020 				pgdat->node_id,
2021 				zone->name);
2022 	for (order = 0; order < MAX_ORDER; ++order) {
2023 		fill_contig_page_info(zone, order, &info);
2024 		index = unusable_free_index(order, &info);
2025 		seq_printf(m, "%d.%03d ", index / 1000, index % 1000);
2026 	}
2027 
2028 	seq_putc(m, '\n');
2029 }
2030 
2031 /*
2032  * Display unusable free space index
2033  *
2034  * The unusable free space index measures how much of the available free
2035  * memory cannot be used to satisfy an allocation of a given size and is a
2036  * value between 0 and 1. The higher the value, the more of free memory is
2037  * unusable and by implication, the worse the external fragmentation is. This
2038  * can be expressed as a percentage by multiplying by 100.
2039  */
2040 static int unusable_show(struct seq_file *m, void *arg)
2041 {
2042 	pg_data_t *pgdat = (pg_data_t *)arg;
2043 
2044 	/* check memoryless node */
2045 	if (!node_state(pgdat->node_id, N_MEMORY))
2046 		return 0;
2047 
2048 	walk_zones_in_node(m, pgdat, true, false, unusable_show_print);
2049 
2050 	return 0;
2051 }
2052 
2053 static const struct seq_operations unusable_op = {
2054 	.start	= frag_start,
2055 	.next	= frag_next,
2056 	.stop	= frag_stop,
2057 	.show	= unusable_show,
2058 };
2059 
2060 static int unusable_open(struct inode *inode, struct file *file)
2061 {
2062 	return seq_open(file, &unusable_op);
2063 }
2064 
2065 static const struct file_operations unusable_file_ops = {
2066 	.open		= unusable_open,
2067 	.read		= seq_read,
2068 	.llseek		= seq_lseek,
2069 	.release	= seq_release,
2070 };
2071 
2072 static void extfrag_show_print(struct seq_file *m,
2073 					pg_data_t *pgdat, struct zone *zone)
2074 {
2075 	unsigned int order;
2076 	int index;
2077 
2078 	/* Alloc on stack as interrupts are disabled for zone walk */
2079 	struct contig_page_info info;
2080 
2081 	seq_printf(m, "Node %d, zone %8s ",
2082 				pgdat->node_id,
2083 				zone->name);
2084 	for (order = 0; order < MAX_ORDER; ++order) {
2085 		fill_contig_page_info(zone, order, &info);
2086 		index = __fragmentation_index(order, &info);
2087 		seq_printf(m, "%d.%03d ", index / 1000, index % 1000);
2088 	}
2089 
2090 	seq_putc(m, '\n');
2091 }
2092 
2093 /*
2094  * Display fragmentation index for orders that allocations would fail for
2095  */
2096 static int extfrag_show(struct seq_file *m, void *arg)
2097 {
2098 	pg_data_t *pgdat = (pg_data_t *)arg;
2099 
2100 	walk_zones_in_node(m, pgdat, true, false, extfrag_show_print);
2101 
2102 	return 0;
2103 }
2104 
2105 static const struct seq_operations extfrag_op = {
2106 	.start	= frag_start,
2107 	.next	= frag_next,
2108 	.stop	= frag_stop,
2109 	.show	= extfrag_show,
2110 };
2111 
2112 static int extfrag_open(struct inode *inode, struct file *file)
2113 {
2114 	return seq_open(file, &extfrag_op);
2115 }
2116 
2117 static const struct file_operations extfrag_file_ops = {
2118 	.open		= extfrag_open,
2119 	.read		= seq_read,
2120 	.llseek		= seq_lseek,
2121 	.release	= seq_release,
2122 };
2123 
2124 static int __init extfrag_debug_init(void)
2125 {
2126 	struct dentry *extfrag_debug_root;
2127 
2128 	extfrag_debug_root = debugfs_create_dir("extfrag", NULL);
2129 
2130 	debugfs_create_file("unusable_index", 0444, extfrag_debug_root, NULL,
2131 			    &unusable_file_ops);
2132 
2133 	debugfs_create_file("extfrag_index", 0444, extfrag_debug_root, NULL,
2134 			    &extfrag_file_ops);
2135 
2136 	return 0;
2137 }
2138 
2139 module_init(extfrag_debug_init);
2140 #endif
2141