aboutsummaryrefslogtreecommitdiff
path: root/mm/list_lru.c
blob: c669d87001a63450de08d1170f7a097612267f4f (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
// SPDX-License-Identifier: GPL-2.0-only
/*
 * Copyright (c) 2013 Red Hat, Inc. and Parallels Inc. All rights reserved.
 * Authors: David Chinner and Glauber Costa
 *
 * Generic LRU infrastructure
 */
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/mm.h>
#include <linux/list_lru.h>
#include <linux/slab.h>
#include <linux/mutex.h>
#include <linux/memcontrol.h>
#include "slab.h"
#include "internal.h"

#ifdef CONFIG_MEMCG_KMEM
static LIST_HEAD(memcg_list_lrus);
static DEFINE_MUTEX(list_lrus_mutex);

static inline bool list_lru_memcg_aware(struct list_lru *lru)
{
	return lru->memcg_aware;
}

static void list_lru_register(struct list_lru *lru)
{
	if (!list_lru_memcg_aware(lru))
		return;

	mutex_lock(&list_lrus_mutex);
	list_add(&lru->list, &memcg_list_lrus);
	mutex_unlock(&list_lrus_mutex);
}

static void list_lru_unregister(struct list_lru *lru)
{
	if (!list_lru_memcg_aware(lru))
		return;

	mutex_lock(&list_lrus_mutex);
	list_del(&lru->list);
	mutex_unlock(&list_lrus_mutex);
}

static int lru_shrinker_id(struct list_lru *lru)
{
	return lru->shrinker_id;
}

static inline struct list_lru_one *
list_lru_from_memcg_idx(struct list_lru *lru, int nid, int idx)
{
	if (list_lru_memcg_aware(lru) && idx >= 0) {
		struct list_lru_memcg *mlru = xa_load(&lru->xa, idx);

		return mlru ? &mlru->node[nid] : NULL;
	}
	return &lru->node[nid].lru;
}

static inline struct list_lru_one *
list_lru_from_kmem(struct list_lru *lru, int nid, void *ptr,
		   struct mem_cgroup **memcg_ptr)
{
	struct list_lru_node *nlru = &lru->node[nid];
	struct list_lru_one *l = &nlru->lru;
	struct mem_cgroup *memcg = NULL;

	if (!list_lru_memcg_aware(lru))
		goto out;

	memcg = mem_cgroup_from_obj(ptr);
	if (!memcg)
		goto out;

	l = list_lru_from_memcg_idx(lru, nid, memcg_kmem_id(memcg));
out:
	if (memcg_ptr)
		*memcg_ptr = memcg;
	return l;
}
#else
static void list_lru_register(struct list_lru *lru)
{
}

static void list_lru_unregister(struct list_lru *lru)
{
}

static int lru_shrinker_id(struct list_lru *lru)
{
	return -1;
}

static inline bool list_lru_memcg_aware(struct list_lru *lru)
{
	return false;
}

static inline struct list_lru_one *
list_lru_from_memcg_idx(struct list_lru *lru, int nid, int idx)
{
	return &lru->node[nid].lru;
}

static inline struct list_lru_one *
list_lru_from_kmem(struct list_lru *lru, int nid, void *ptr,
		   struct mem_cgroup **memcg_ptr)
{
	if (memcg_ptr)
		*memcg_ptr = NULL;
	return &lru->node[nid].lru;
}
#endif /* CONFIG_MEMCG_KMEM */

bool list_lru_add(struct list_lru *lru, struct list_head *item)
{
	int nid = page_to_nid(virt_to_page(item));
	struct list_lru_node *nlru = &lru->node[nid];
	struct mem_cgroup *memcg;
	struct list_lru_one *l;

	spin_lock(&nlru->lock);
	if (list_empty(item)) {
		l = list_lru_from_kmem(lru, nid, item, &memcg);
		list_add_tail(item, &l->list);
		/* Set shrinker bit if the first element was added */
		if (!l->nr_items++)
			set_shrinker_bit(memcg, nid,
					 lru_shrinker_id(lru));
		nlru->nr_items++;
		spin_unlock(&nlru->lock);
		return true;
	}
	spin_unlock(&nlru->lock);
	return false;
}
EXPORT_SYMBOL_GPL(list_lru_add);

bool list_lru_del(struct list_lru *lru, struct list_head *item)
{
	int nid = page_to_nid(virt_to_page(item));
	struct list_lru_node *nlru = &lru->node[nid];
	struct list_lru_one *l;

	spin_lock(&nlru->lock);
	if (!list_empty(item)) {
		l = list_lru_from_kmem(lru, nid, item, NULL);
		list_del_init(item);
		l->nr_items--;
		nlru->nr_items--;
		spin_unlock(&nlru->lock);
		return true;
	}
	spin_unlock(&nlru->lock);
	return false;
}
EXPORT_SYMBOL_GPL(list_lru_del);

void list_lru_isolate(struct list_lru_one *list, struct list_head *item)
{
	list_del_init(item);
	list->nr_items--;
}
EXPORT_SYMBOL_GPL(list_lru_isolate);

void list_lru_isolate_move(struct list_lru_one *list, struct list_head *item,
			   struct list_head *head)
{
	list_move(item, head);
	list->nr_items--;
}
EXPORT_SYMBOL_GPL(list_lru_isolate_move);

unsigned long list_lru_count_one(struct list_lru *lru,
				 int nid, struct mem_cgroup *memcg)
{
	struct list_lru_one *l;
	long count;

	rcu_read_lock();
	l = list_lru_from_memcg_idx(lru, nid, memcg_kmem_id(memcg));
	count = l ? READ_ONCE(l->nr_items) : 0;
	rcu_read_unlock();

	if (unlikely(count < 0))
		count = 0;

	return count;
}
EXPORT_SYMBOL_GPL(list_lru_count_one);

unsigned long list_lru_count_node(struct list_lru *lru, int nid)
{
	struct list_lru_node *nlru;

	nlru = &lru->node[nid];
	return nlru->nr_items;
}
EXPORT_SYMBOL_GPL(list_lru_count_node);

static unsigned long
__list_lru_walk_one(struct list_lru *lru, int nid, int memcg_idx,
		    list_lru_walk_cb isolate, void *cb_arg,
		    unsigned long *nr_to_walk)
{
	struct list_lru_node *nlru = &lru->node[nid];
	struct list_lru_one *l;
	struct list_head *item, *n;
	unsigned long isolated = 0;

restart:
	l = list_lru_from_memcg_idx(lru, nid, memcg_idx);
	if (!l)
		goto out;

	list_for_each_safe(item, n, &l->list) {
		enum lru_status ret;

		/*
		 * decrement nr_to_walk first so that we don't livelock if we
		 * get stuck on large numbers of LRU_RETRY items
		 */
		if (!*nr_to_walk)
			break;
		--*nr_to_walk;

		ret = isolate(item, l, &nlru->lock, cb_arg);
		switch (ret) {
		case LRU_REMOVED_RETRY:
			assert_spin_locked(&nlru->lock);
			fallthrough;
		case LRU_REMOVED:
			isolated++;
			nlru->nr_items--;
			/*
			 * If the lru lock has been dropped, our list
			 * traversal is now invalid and so we have to
			 * restart from scratch.
			 */
			if (ret == LRU_REMOVED_RETRY)
				goto restart;
			break;
		case LRU_ROTATE:
			list_move_tail(item, &l->list);
			break;
		case LRU_SKIP:
			break;
		case LRU_RETRY:
			/*
			 * The lru lock has been dropped, our list traversal is
			 * now invalid and so we have to restart from scratch.
			 */
			assert_spin_locked(&nlru->lock);
			goto restart;
		default:
			BUG();
		}
	}
out:
	return isolated;
}

unsigned long
list_lru_walk_one(struct list_lru *lru, int nid, struct mem_cgroup *memcg,
		  list_lru_walk_cb isolate, void *cb_arg,
		  unsigned long *nr_to_walk)
{
	struct list_lru_node *nlru = &lru->node[nid];
	unsigned long ret;

	spin_lock(&nlru->lock);
	ret = __list_lru_walk_one(lru, nid, memcg_kmem_id(memcg), isolate,
				  cb_arg, nr_to_walk);
	spin_unlock(&nlru->lock);
	return ret;
}
EXPORT_SYMBOL_GPL(list_lru_walk_one);

unsigned long
list_lru_walk_one_irq(struct list_lru *lru, int nid, struct mem_cgroup *memcg,
		      list_lru_walk_cb isolate, void *cb_arg,
		      unsigned long *nr_to_walk)
{
	struct list_lru_node *nlru = &lru->node[nid];
	unsigned long ret;

	spin_lock_irq(&nlru->lock);
	ret = __list_lru_walk_one(lru, nid, memcg_kmem_id(memcg), isolate,
				  cb_arg, nr_to_walk);
	spin_unlock_irq(&nlru->lock);
	return ret;
}

unsigned long list_lru_walk_node(struct list_lru *lru, int nid,
				 list_lru_walk_cb isolate, void *cb_arg,
				 unsigned long *nr_to_walk)
{
	long isolated = 0;

	isolated += list_lru_walk_one(lru, nid, NULL, isolate, cb_arg,
				      nr_to_walk);

#ifdef CONFIG_MEMCG_KMEM
	if (*nr_to_walk > 0 && list_lru_memcg_aware(lru)) {
		struct list_lru_memcg *mlru;
		unsigned long index;

		xa_for_each(&lru->xa, index, mlru) {
			struct list_lru_node *nlru = &lru->node[nid];

			spin_lock(&nlru->lock);
			isolated += __list_lru_walk_one(lru, nid, index,
							isolate, cb_arg,
							nr_to_walk);
			spin_unlock(&nlru->lock);

			if (*nr_to_walk <= 0)
				break;
		}
	}
#endif

	return isolated;
}
EXPORT_SYMBOL_GPL(list_lru_walk_node);

static void init_one_lru(struct list_lru_one *l)
{
	INIT_LIST_HEAD(&l->list);
	l->nr_items = 0;
}

#ifdef CONFIG_MEMCG_KMEM
static struct list_lru_memcg *memcg_init_list_lru_one(gfp_t gfp)
{
	int nid;
	struct list_lru_memcg *mlru;

	mlru = kmalloc(struct_size(mlru, node, nr_node_ids), gfp);
	if (!mlru)
		return NULL;

	for_each_node(nid)
		init_one_lru(&mlru->node[nid]);

	return mlru;
}

static void memcg_list_lru_free(struct list_lru *lru, int src_idx)
{
	struct list_lru_memcg *mlru = xa_erase_irq(&lru->xa, src_idx);

	/*
	 * The __list_lru_walk_one() can walk the list of this node.
	 * We need kvfree_rcu() here. And the walking of the list
	 * is under lru->node[nid]->lock, which can serve as a RCU
	 * read-side critical section.
	 */
	if (mlru)
		kvfree_rcu(mlru, rcu);
}

static inline void memcg_init_list_lru(struct list_lru *lru, bool memcg_aware)
{
	if (memcg_aware)
		xa_init_flags(&lru->xa, XA_FLAGS_LOCK_IRQ);
	lru->memcg_aware = memcg_aware;
}

static void memcg_destroy_list_lru(struct list_lru *lru)
{
	XA_STATE(xas, &lru->xa, 0);
	struct list_lru_memcg *mlru;

	if (!list_lru_memcg_aware(lru))
		return;

	xas_lock_irq(&xas);
	xas_for_each(&xas, mlru, ULONG_MAX) {
		kfree(mlru);
		xas_store(&xas, NULL);
	}
	xas_unlock_irq(&xas);
}

static void memcg_reparent_list_lru_node(struct list_lru *lru, int nid,
					 int src_idx, struct mem_cgroup *dst_memcg)
{
	struct list_lru_node *nlru = &lru->node[nid];
	int dst_idx = dst_memcg->kmemcg_id;
	struct list_lru_one *src, *dst;

	/*
	 * If there is no lru entry in this nlru, we can skip it immediately.
	 */
	if (!READ_ONCE(nlru->nr_items))
		return;

	/*
	 * Since list_lru_{add,del} may be called under an IRQ-safe lock,
	 * we have to use IRQ-safe primitives here to avoid deadlock.
	 */
	spin_lock_irq(&nlru->lock);

	src = list_lru_from_memcg_idx(lru, nid, src_idx);
	if (!src)
		goto out;
	dst = list_lru_from_memcg_idx(lru, nid, dst_idx);

	list_splice_init(&src->list, &dst->list);

	if (src->nr_items) {
		dst->nr_items += src->nr_items;
		set_shrinker_bit(dst_memcg, nid, lru_shrinker_id(lru));
		src->nr_items = 0;
	}
out:
	spin_unlock_irq(&nlru->lock);
}

static void memcg_reparent_list_lru(struct list_lru *lru,
				    int src_idx, struct mem_cgroup *dst_memcg)
{
	int i;

	for_each_node(i)
		memcg_reparent_list_lru_node(lru, i, src_idx, dst_memcg);

	memcg_list_lru_free(lru, src_idx);
}

void memcg_reparent_list_lrus(struct mem_cgroup *memcg, struct mem_cgroup *parent)
{
	struct cgroup_subsys_state *css;
	struct list_lru *lru;
	int src_idx = memcg->kmemcg_id;

	/*
	 * Change kmemcg_id of this cgroup and all its descendants to the
	 * parent's id, and then move all entries from this cgroup's list_lrus
	 * to ones of the parent.
	 *
	 * After we have finished, all list_lrus corresponding to this cgroup
	 * are guaranteed to remain empty. So we can safely free this cgroup's
	 * list lrus in memcg_list_lru_free().
	 *
	 * Changing ->kmemcg_id to the parent can prevent memcg_list_lru_alloc()
	 * from allocating list lrus for this cgroup after memcg_list_lru_free()
	 * call.
	 */
	rcu_read_lock();
	css_for_each_descendant_pre(css, &memcg->css) {
		struct mem_cgroup *child;

		child = mem_cgroup_from_css(css);
		WRITE_ONCE(child->kmemcg_id, parent->kmemcg_id);
	}
	rcu_read_unlock();

	mutex_lock(&list_lrus_mutex);
	list_for_each_entry(lru, &memcg_list_lrus, list)
		memcg_reparent_list_lru(lru, src_idx, parent);
	mutex_unlock(&list_lrus_mutex);
}

static inline bool memcg_list_lru_allocated(struct mem_cgroup *memcg,
					    struct list_lru *lru)
{
	int idx = memcg->kmemcg_id;

	return idx < 0 || xa_load(&lru->xa, idx);
}

int memcg_list_lru_alloc(struct mem_cgroup *memcg, struct list_lru *lru,
			 gfp_t gfp)
{
	int i;
	unsigned long flags;
	struct list_lru_memcg_table {
		struct list_lru_memcg *mlru;
		struct mem_cgroup *memcg;
	} *table;
	XA_STATE(xas, &lru->xa, 0);

	if (!list_lru_memcg_aware(lru) || memcg_list_lru_allocated(memcg, lru))
		return 0;

	gfp &= GFP_RECLAIM_MASK;
	table = kmalloc_array(memcg->css.cgroup->level, sizeof(*table), gfp);
	if (!table)
		return -ENOMEM;

	/*
	 * Because the list_lru can be reparented to the parent cgroup's
	 * list_lru, we should make sure that this cgroup and all its
	 * ancestors have allocated list_lru_memcg.
	 */
	for (i = 0; memcg; memcg = parent_mem_cgroup(memcg), i++) {
		if (memcg_list_lru_allocated(memcg, lru))
			break;

		table[i].memcg = memcg;
		table[i].mlru = memcg_init_list_lru_one(gfp);
		if (!table[i].mlru) {
			while (i--)
				kfree(table[i].mlru);
			kfree(table);
			return -ENOMEM;
		}
	}

	xas_lock_irqsave(&xas, flags);
	while (i--) {
		int index = READ_ONCE(table[i].memcg->kmemcg_id);
		struct list_lru_memcg *mlru = table[i].mlru;

		xas_set(&xas, index);
retry:
		if (unlikely(index < 0 || xas_error(&xas) || xas_load(&xas))) {
			kfree(mlru);
		} else {
			xas_store(&xas, mlru);
			if (xas_error(&xas) == -ENOMEM) {
				xas_unlock_irqrestore(&xas, flags);
				if (xas_nomem(&xas, gfp))
					xas_set_err(&xas, 0);
				xas_lock_irqsave(&xas, flags);
				/*
				 * The xas lock has been released, this memcg
				 * can be reparented before us. So reload
				 * memcg id. More details see the comments
				 * in memcg_reparent_list_lrus().
				 */
				index = READ_ONCE(table[i].memcg->kmemcg_id);
				if (index < 0)
					xas_set_err(&xas, 0);
				else if (!xas_error(&xas) && index != xas.xa_index)
					xas_set(&xas, index);
				goto retry;
			}
		}
	}
	/* xas_nomem() is used to free memory instead of memory allocation. */
	if (xas.xa_alloc)
		xas_nomem(&xas, gfp);
	xas_unlock_irqrestore(&xas, flags);
	kfree(table);

	return xas_error(&xas);
}
#else
static inline void memcg_init_list_lru(struct list_lru *lru, bool memcg_aware)
{
}

static void memcg_destroy_list_lru(struct list_lru *lru)
{
}
#endif /* CONFIG_MEMCG_KMEM */

int __list_lru_init(struct list_lru *lru, bool memcg_aware,
		    struct lock_class_key *key, struct shrinker *shrinker)
{
	int i;

#ifdef CONFIG_MEMCG_KMEM
	if (shrinker)
		lru->shrinker_id = shrinker->id;
	else
		lru->shrinker_id = -1;
#endif

	lru->node = kcalloc(nr_node_ids, sizeof(*lru->node), GFP_KERNEL);
	if (!lru->node)
		return -ENOMEM;

	for_each_node(i) {
		spin_lock_init(&lru->node[i].lock);
		if (key)
			lockdep_set_class(&lru->node[i].lock, key);
		init_one_lru(&lru->node[i].lru);
	}

	memcg_init_list_lru(lru, memcg_aware);
	list_lru_register(lru);

	return 0;
}
EXPORT_SYMBOL_GPL(__list_lru_init);

void list_lru_destroy(struct list_lru *lru)
{
	/* Already destroyed or not yet initialized? */
	if (!lru->node)
		return;

	list_lru_unregister(lru);

	memcg_destroy_list_lru(lru);
	kfree(lru->node);
	lru->node = NULL;

#ifdef CONFIG_MEMCG_KMEM
	lru->shrinker_id = -1;
#endif
}
EXPORT_SYMBOL_GPL(list_lru_destroy);