Merge tag 'block-6.0-2022-08-12' of git://git.kernel.dk/linux-block
[platform/kernel/linux-starfive.git] / mm / list_lru.c
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Copyright (c) 2013 Red Hat, Inc. and Parallels Inc. All rights reserved.
4  * Authors: David Chinner and Glauber Costa
5  *
6  * Generic LRU infrastructure
7  */
8 #include <linux/kernel.h>
9 #include <linux/module.h>
10 #include <linux/mm.h>
11 #include <linux/list_lru.h>
12 #include <linux/slab.h>
13 #include <linux/mutex.h>
14 #include <linux/memcontrol.h>
15 #include "slab.h"
16 #include "internal.h"
17
18 #ifdef CONFIG_MEMCG_KMEM
19 static LIST_HEAD(memcg_list_lrus);
20 static DEFINE_MUTEX(list_lrus_mutex);
21
22 static inline bool list_lru_memcg_aware(struct list_lru *lru)
23 {
24         return lru->memcg_aware;
25 }
26
27 static void list_lru_register(struct list_lru *lru)
28 {
29         if (!list_lru_memcg_aware(lru))
30                 return;
31
32         mutex_lock(&list_lrus_mutex);
33         list_add(&lru->list, &memcg_list_lrus);
34         mutex_unlock(&list_lrus_mutex);
35 }
36
37 static void list_lru_unregister(struct list_lru *lru)
38 {
39         if (!list_lru_memcg_aware(lru))
40                 return;
41
42         mutex_lock(&list_lrus_mutex);
43         list_del(&lru->list);
44         mutex_unlock(&list_lrus_mutex);
45 }
46
47 static int lru_shrinker_id(struct list_lru *lru)
48 {
49         return lru->shrinker_id;
50 }
51
52 static inline struct list_lru_one *
53 list_lru_from_memcg_idx(struct list_lru *lru, int nid, int idx)
54 {
55         if (list_lru_memcg_aware(lru) && idx >= 0) {
56                 struct list_lru_memcg *mlru = xa_load(&lru->xa, idx);
57
58                 return mlru ? &mlru->node[nid] : NULL;
59         }
60         return &lru->node[nid].lru;
61 }
62
63 static inline struct list_lru_one *
64 list_lru_from_kmem(struct list_lru *lru, int nid, void *ptr,
65                    struct mem_cgroup **memcg_ptr)
66 {
67         struct list_lru_node *nlru = &lru->node[nid];
68         struct list_lru_one *l = &nlru->lru;
69         struct mem_cgroup *memcg = NULL;
70
71         if (!list_lru_memcg_aware(lru))
72                 goto out;
73
74         memcg = mem_cgroup_from_slab_obj(ptr);
75         if (!memcg)
76                 goto out;
77
78         l = list_lru_from_memcg_idx(lru, nid, memcg_kmem_id(memcg));
79 out:
80         if (memcg_ptr)
81                 *memcg_ptr = memcg;
82         return l;
83 }
84 #else
85 static void list_lru_register(struct list_lru *lru)
86 {
87 }
88
89 static void list_lru_unregister(struct list_lru *lru)
90 {
91 }
92
93 static int lru_shrinker_id(struct list_lru *lru)
94 {
95         return -1;
96 }
97
98 static inline bool list_lru_memcg_aware(struct list_lru *lru)
99 {
100         return false;
101 }
102
103 static inline struct list_lru_one *
104 list_lru_from_memcg_idx(struct list_lru *lru, int nid, int idx)
105 {
106         return &lru->node[nid].lru;
107 }
108
109 static inline struct list_lru_one *
110 list_lru_from_kmem(struct list_lru *lru, int nid, void *ptr,
111                    struct mem_cgroup **memcg_ptr)
112 {
113         if (memcg_ptr)
114                 *memcg_ptr = NULL;
115         return &lru->node[nid].lru;
116 }
117 #endif /* CONFIG_MEMCG_KMEM */
118
119 bool list_lru_add(struct list_lru *lru, struct list_head *item)
120 {
121         int nid = page_to_nid(virt_to_page(item));
122         struct list_lru_node *nlru = &lru->node[nid];
123         struct mem_cgroup *memcg;
124         struct list_lru_one *l;
125
126         spin_lock(&nlru->lock);
127         if (list_empty(item)) {
128                 l = list_lru_from_kmem(lru, nid, item, &memcg);
129                 list_add_tail(item, &l->list);
130                 /* Set shrinker bit if the first element was added */
131                 if (!l->nr_items++)
132                         set_shrinker_bit(memcg, nid,
133                                          lru_shrinker_id(lru));
134                 nlru->nr_items++;
135                 spin_unlock(&nlru->lock);
136                 return true;
137         }
138         spin_unlock(&nlru->lock);
139         return false;
140 }
141 EXPORT_SYMBOL_GPL(list_lru_add);
142
143 bool list_lru_del(struct list_lru *lru, struct list_head *item)
144 {
145         int nid = page_to_nid(virt_to_page(item));
146         struct list_lru_node *nlru = &lru->node[nid];
147         struct list_lru_one *l;
148
149         spin_lock(&nlru->lock);
150         if (!list_empty(item)) {
151                 l = list_lru_from_kmem(lru, nid, item, NULL);
152                 list_del_init(item);
153                 l->nr_items--;
154                 nlru->nr_items--;
155                 spin_unlock(&nlru->lock);
156                 return true;
157         }
158         spin_unlock(&nlru->lock);
159         return false;
160 }
161 EXPORT_SYMBOL_GPL(list_lru_del);
162
163 void list_lru_isolate(struct list_lru_one *list, struct list_head *item)
164 {
165         list_del_init(item);
166         list->nr_items--;
167 }
168 EXPORT_SYMBOL_GPL(list_lru_isolate);
169
170 void list_lru_isolate_move(struct list_lru_one *list, struct list_head *item,
171                            struct list_head *head)
172 {
173         list_move(item, head);
174         list->nr_items--;
175 }
176 EXPORT_SYMBOL_GPL(list_lru_isolate_move);
177
178 unsigned long list_lru_count_one(struct list_lru *lru,
179                                  int nid, struct mem_cgroup *memcg)
180 {
181         struct list_lru_one *l;
182         long count;
183
184         rcu_read_lock();
185         l = list_lru_from_memcg_idx(lru, nid, memcg_kmem_id(memcg));
186         count = l ? READ_ONCE(l->nr_items) : 0;
187         rcu_read_unlock();
188
189         if (unlikely(count < 0))
190                 count = 0;
191
192         return count;
193 }
194 EXPORT_SYMBOL_GPL(list_lru_count_one);
195
196 unsigned long list_lru_count_node(struct list_lru *lru, int nid)
197 {
198         struct list_lru_node *nlru;
199
200         nlru = &lru->node[nid];
201         return nlru->nr_items;
202 }
203 EXPORT_SYMBOL_GPL(list_lru_count_node);
204
205 static unsigned long
206 __list_lru_walk_one(struct list_lru *lru, int nid, int memcg_idx,
207                     list_lru_walk_cb isolate, void *cb_arg,
208                     unsigned long *nr_to_walk)
209 {
210         struct list_lru_node *nlru = &lru->node[nid];
211         struct list_lru_one *l;
212         struct list_head *item, *n;
213         unsigned long isolated = 0;
214
215 restart:
216         l = list_lru_from_memcg_idx(lru, nid, memcg_idx);
217         if (!l)
218                 goto out;
219
220         list_for_each_safe(item, n, &l->list) {
221                 enum lru_status ret;
222
223                 /*
224                  * decrement nr_to_walk first so that we don't livelock if we
225                  * get stuck on large numbers of LRU_RETRY items
226                  */
227                 if (!*nr_to_walk)
228                         break;
229                 --*nr_to_walk;
230
231                 ret = isolate(item, l, &nlru->lock, cb_arg);
232                 switch (ret) {
233                 case LRU_REMOVED_RETRY:
234                         assert_spin_locked(&nlru->lock);
235                         fallthrough;
236                 case LRU_REMOVED:
237                         isolated++;
238                         nlru->nr_items--;
239                         /*
240                          * If the lru lock has been dropped, our list
241                          * traversal is now invalid and so we have to
242                          * restart from scratch.
243                          */
244                         if (ret == LRU_REMOVED_RETRY)
245                                 goto restart;
246                         break;
247                 case LRU_ROTATE:
248                         list_move_tail(item, &l->list);
249                         break;
250                 case LRU_SKIP:
251                         break;
252                 case LRU_RETRY:
253                         /*
254                          * The lru lock has been dropped, our list traversal is
255                          * now invalid and so we have to restart from scratch.
256                          */
257                         assert_spin_locked(&nlru->lock);
258                         goto restart;
259                 default:
260                         BUG();
261                 }
262         }
263 out:
264         return isolated;
265 }
266
267 unsigned long
268 list_lru_walk_one(struct list_lru *lru, int nid, struct mem_cgroup *memcg,
269                   list_lru_walk_cb isolate, void *cb_arg,
270                   unsigned long *nr_to_walk)
271 {
272         struct list_lru_node *nlru = &lru->node[nid];
273         unsigned long ret;
274
275         spin_lock(&nlru->lock);
276         ret = __list_lru_walk_one(lru, nid, memcg_kmem_id(memcg), isolate,
277                                   cb_arg, nr_to_walk);
278         spin_unlock(&nlru->lock);
279         return ret;
280 }
281 EXPORT_SYMBOL_GPL(list_lru_walk_one);
282
283 unsigned long
284 list_lru_walk_one_irq(struct list_lru *lru, int nid, struct mem_cgroup *memcg,
285                       list_lru_walk_cb isolate, void *cb_arg,
286                       unsigned long *nr_to_walk)
287 {
288         struct list_lru_node *nlru = &lru->node[nid];
289         unsigned long ret;
290
291         spin_lock_irq(&nlru->lock);
292         ret = __list_lru_walk_one(lru, nid, memcg_kmem_id(memcg), isolate,
293                                   cb_arg, nr_to_walk);
294         spin_unlock_irq(&nlru->lock);
295         return ret;
296 }
297
298 unsigned long list_lru_walk_node(struct list_lru *lru, int nid,
299                                  list_lru_walk_cb isolate, void *cb_arg,
300                                  unsigned long *nr_to_walk)
301 {
302         long isolated = 0;
303
304         isolated += list_lru_walk_one(lru, nid, NULL, isolate, cb_arg,
305                                       nr_to_walk);
306
307 #ifdef CONFIG_MEMCG_KMEM
308         if (*nr_to_walk > 0 && list_lru_memcg_aware(lru)) {
309                 struct list_lru_memcg *mlru;
310                 unsigned long index;
311
312                 xa_for_each(&lru->xa, index, mlru) {
313                         struct list_lru_node *nlru = &lru->node[nid];
314
315                         spin_lock(&nlru->lock);
316                         isolated += __list_lru_walk_one(lru, nid, index,
317                                                         isolate, cb_arg,
318                                                         nr_to_walk);
319                         spin_unlock(&nlru->lock);
320
321                         if (*nr_to_walk <= 0)
322                                 break;
323                 }
324         }
325 #endif
326
327         return isolated;
328 }
329 EXPORT_SYMBOL_GPL(list_lru_walk_node);
330
331 static void init_one_lru(struct list_lru_one *l)
332 {
333         INIT_LIST_HEAD(&l->list);
334         l->nr_items = 0;
335 }
336
337 #ifdef CONFIG_MEMCG_KMEM
338 static struct list_lru_memcg *memcg_init_list_lru_one(gfp_t gfp)
339 {
340         int nid;
341         struct list_lru_memcg *mlru;
342
343         mlru = kmalloc(struct_size(mlru, node, nr_node_ids), gfp);
344         if (!mlru)
345                 return NULL;
346
347         for_each_node(nid)
348                 init_one_lru(&mlru->node[nid]);
349
350         return mlru;
351 }
352
353 static void memcg_list_lru_free(struct list_lru *lru, int src_idx)
354 {
355         struct list_lru_memcg *mlru = xa_erase_irq(&lru->xa, src_idx);
356
357         /*
358          * The __list_lru_walk_one() can walk the list of this node.
359          * We need kvfree_rcu() here. And the walking of the list
360          * is under lru->node[nid]->lock, which can serve as a RCU
361          * read-side critical section.
362          */
363         if (mlru)
364                 kvfree_rcu(mlru, rcu);
365 }
366
367 static inline void memcg_init_list_lru(struct list_lru *lru, bool memcg_aware)
368 {
369         if (memcg_aware)
370                 xa_init_flags(&lru->xa, XA_FLAGS_LOCK_IRQ);
371         lru->memcg_aware = memcg_aware;
372 }
373
374 static void memcg_destroy_list_lru(struct list_lru *lru)
375 {
376         XA_STATE(xas, &lru->xa, 0);
377         struct list_lru_memcg *mlru;
378
379         if (!list_lru_memcg_aware(lru))
380                 return;
381
382         xas_lock_irq(&xas);
383         xas_for_each(&xas, mlru, ULONG_MAX) {
384                 kfree(mlru);
385                 xas_store(&xas, NULL);
386         }
387         xas_unlock_irq(&xas);
388 }
389
390 static void memcg_reparent_list_lru_node(struct list_lru *lru, int nid,
391                                          int src_idx, struct mem_cgroup *dst_memcg)
392 {
393         struct list_lru_node *nlru = &lru->node[nid];
394         int dst_idx = dst_memcg->kmemcg_id;
395         struct list_lru_one *src, *dst;
396
397         /*
398          * Since list_lru_{add,del} may be called under an IRQ-safe lock,
399          * we have to use IRQ-safe primitives here to avoid deadlock.
400          */
401         spin_lock_irq(&nlru->lock);
402
403         src = list_lru_from_memcg_idx(lru, nid, src_idx);
404         if (!src)
405                 goto out;
406         dst = list_lru_from_memcg_idx(lru, nid, dst_idx);
407
408         list_splice_init(&src->list, &dst->list);
409
410         if (src->nr_items) {
411                 dst->nr_items += src->nr_items;
412                 set_shrinker_bit(dst_memcg, nid, lru_shrinker_id(lru));
413                 src->nr_items = 0;
414         }
415 out:
416         spin_unlock_irq(&nlru->lock);
417 }
418
419 static void memcg_reparent_list_lru(struct list_lru *lru,
420                                     int src_idx, struct mem_cgroup *dst_memcg)
421 {
422         int i;
423
424         for_each_node(i)
425                 memcg_reparent_list_lru_node(lru, i, src_idx, dst_memcg);
426
427         memcg_list_lru_free(lru, src_idx);
428 }
429
430 void memcg_reparent_list_lrus(struct mem_cgroup *memcg, struct mem_cgroup *parent)
431 {
432         struct cgroup_subsys_state *css;
433         struct list_lru *lru;
434         int src_idx = memcg->kmemcg_id;
435
436         /*
437          * Change kmemcg_id of this cgroup and all its descendants to the
438          * parent's id, and then move all entries from this cgroup's list_lrus
439          * to ones of the parent.
440          *
441          * After we have finished, all list_lrus corresponding to this cgroup
442          * are guaranteed to remain empty. So we can safely free this cgroup's
443          * list lrus in memcg_list_lru_free().
444          *
445          * Changing ->kmemcg_id to the parent can prevent memcg_list_lru_alloc()
446          * from allocating list lrus for this cgroup after memcg_list_lru_free()
447          * call.
448          */
449         rcu_read_lock();
450         css_for_each_descendant_pre(css, &memcg->css) {
451                 struct mem_cgroup *child;
452
453                 child = mem_cgroup_from_css(css);
454                 WRITE_ONCE(child->kmemcg_id, parent->kmemcg_id);
455         }
456         rcu_read_unlock();
457
458         mutex_lock(&list_lrus_mutex);
459         list_for_each_entry(lru, &memcg_list_lrus, list)
460                 memcg_reparent_list_lru(lru, src_idx, parent);
461         mutex_unlock(&list_lrus_mutex);
462 }
463
464 static inline bool memcg_list_lru_allocated(struct mem_cgroup *memcg,
465                                             struct list_lru *lru)
466 {
467         int idx = memcg->kmemcg_id;
468
469         return idx < 0 || xa_load(&lru->xa, idx);
470 }
471
472 int memcg_list_lru_alloc(struct mem_cgroup *memcg, struct list_lru *lru,
473                          gfp_t gfp)
474 {
475         int i;
476         unsigned long flags;
477         struct list_lru_memcg_table {
478                 struct list_lru_memcg *mlru;
479                 struct mem_cgroup *memcg;
480         } *table;
481         XA_STATE(xas, &lru->xa, 0);
482
483         if (!list_lru_memcg_aware(lru) || memcg_list_lru_allocated(memcg, lru))
484                 return 0;
485
486         gfp &= GFP_RECLAIM_MASK;
487         table = kmalloc_array(memcg->css.cgroup->level, sizeof(*table), gfp);
488         if (!table)
489                 return -ENOMEM;
490
491         /*
492          * Because the list_lru can be reparented to the parent cgroup's
493          * list_lru, we should make sure that this cgroup and all its
494          * ancestors have allocated list_lru_memcg.
495          */
496         for (i = 0; memcg; memcg = parent_mem_cgroup(memcg), i++) {
497                 if (memcg_list_lru_allocated(memcg, lru))
498                         break;
499
500                 table[i].memcg = memcg;
501                 table[i].mlru = memcg_init_list_lru_one(gfp);
502                 if (!table[i].mlru) {
503                         while (i--)
504                                 kfree(table[i].mlru);
505                         kfree(table);
506                         return -ENOMEM;
507                 }
508         }
509
510         xas_lock_irqsave(&xas, flags);
511         while (i--) {
512                 int index = READ_ONCE(table[i].memcg->kmemcg_id);
513                 struct list_lru_memcg *mlru = table[i].mlru;
514
515                 xas_set(&xas, index);
516 retry:
517                 if (unlikely(index < 0 || xas_error(&xas) || xas_load(&xas))) {
518                         kfree(mlru);
519                 } else {
520                         xas_store(&xas, mlru);
521                         if (xas_error(&xas) == -ENOMEM) {
522                                 xas_unlock_irqrestore(&xas, flags);
523                                 if (xas_nomem(&xas, gfp))
524                                         xas_set_err(&xas, 0);
525                                 xas_lock_irqsave(&xas, flags);
526                                 /*
527                                  * The xas lock has been released, this memcg
528                                  * can be reparented before us. So reload
529                                  * memcg id. More details see the comments
530                                  * in memcg_reparent_list_lrus().
531                                  */
532                                 index = READ_ONCE(table[i].memcg->kmemcg_id);
533                                 if (index < 0)
534                                         xas_set_err(&xas, 0);
535                                 else if (!xas_error(&xas) && index != xas.xa_index)
536                                         xas_set(&xas, index);
537                                 goto retry;
538                         }
539                 }
540         }
541         /* xas_nomem() is used to free memory instead of memory allocation. */
542         if (xas.xa_alloc)
543                 xas_nomem(&xas, gfp);
544         xas_unlock_irqrestore(&xas, flags);
545         kfree(table);
546
547         return xas_error(&xas);
548 }
549 #else
550 static inline void memcg_init_list_lru(struct list_lru *lru, bool memcg_aware)
551 {
552 }
553
554 static void memcg_destroy_list_lru(struct list_lru *lru)
555 {
556 }
557 #endif /* CONFIG_MEMCG_KMEM */
558
559 int __list_lru_init(struct list_lru *lru, bool memcg_aware,
560                     struct lock_class_key *key, struct shrinker *shrinker)
561 {
562         int i;
563
564 #ifdef CONFIG_MEMCG_KMEM
565         if (shrinker)
566                 lru->shrinker_id = shrinker->id;
567         else
568                 lru->shrinker_id = -1;
569 #endif
570
571         lru->node = kcalloc(nr_node_ids, sizeof(*lru->node), GFP_KERNEL);
572         if (!lru->node)
573                 return -ENOMEM;
574
575         for_each_node(i) {
576                 spin_lock_init(&lru->node[i].lock);
577                 if (key)
578                         lockdep_set_class(&lru->node[i].lock, key);
579                 init_one_lru(&lru->node[i].lru);
580         }
581
582         memcg_init_list_lru(lru, memcg_aware);
583         list_lru_register(lru);
584
585         return 0;
586 }
587 EXPORT_SYMBOL_GPL(__list_lru_init);
588
589 void list_lru_destroy(struct list_lru *lru)
590 {
591         /* Already destroyed or not yet initialized? */
592         if (!lru->node)
593                 return;
594
595         list_lru_unregister(lru);
596
597         memcg_destroy_list_lru(lru);
598         kfree(lru->node);
599         lru->node = NULL;
600
601 #ifdef CONFIG_MEMCG_KMEM
602         lru->shrinker_id = -1;
603 #endif
604 }
605 EXPORT_SYMBOL_GPL(list_lru_destroy);