mm/list_lru.c: mark expected switch fall-through
[sfrench/cifs-2.6.git] / mm / list_lru.c
1 /*
2  * Copyright (c) 2013 Red Hat, Inc. and Parallels Inc. All rights reserved.
3  * Authors: David Chinner and Glauber Costa
4  *
5  * Generic LRU infrastructure
6  */
7 #include <linux/kernel.h>
8 #include <linux/module.h>
9 #include <linux/mm.h>
10 #include <linux/list_lru.h>
11 #include <linux/slab.h>
12 #include <linux/mutex.h>
13 #include <linux/memcontrol.h>
14
15 #if defined(CONFIG_MEMCG) && !defined(CONFIG_SLOB)
16 static LIST_HEAD(list_lrus);
17 static DEFINE_MUTEX(list_lrus_mutex);
18
19 static void list_lru_register(struct list_lru *lru)
20 {
21         mutex_lock(&list_lrus_mutex);
22         list_add(&lru->list, &list_lrus);
23         mutex_unlock(&list_lrus_mutex);
24 }
25
26 static void list_lru_unregister(struct list_lru *lru)
27 {
28         mutex_lock(&list_lrus_mutex);
29         list_del(&lru->list);
30         mutex_unlock(&list_lrus_mutex);
31 }
32 #else
33 static void list_lru_register(struct list_lru *lru)
34 {
35 }
36
37 static void list_lru_unregister(struct list_lru *lru)
38 {
39 }
40 #endif /* CONFIG_MEMCG && !CONFIG_SLOB */
41
42 #if defined(CONFIG_MEMCG) && !defined(CONFIG_SLOB)
43 static inline bool list_lru_memcg_aware(struct list_lru *lru)
44 {
45         /*
46          * This needs node 0 to be always present, even
47          * in the systems supporting sparse numa ids.
48          */
49         return !!lru->node[0].memcg_lrus;
50 }
51
52 static inline struct list_lru_one *
53 list_lru_from_memcg_idx(struct list_lru_node *nlru, int idx)
54 {
55         /*
56          * The lock protects the array of per cgroup lists from relocation
57          * (see memcg_update_list_lru_node).
58          */
59         lockdep_assert_held(&nlru->lock);
60         if (nlru->memcg_lrus && idx >= 0)
61                 return nlru->memcg_lrus->lru[idx];
62
63         return &nlru->lru;
64 }
65
66 static __always_inline struct mem_cgroup *mem_cgroup_from_kmem(void *ptr)
67 {
68         struct page *page;
69
70         if (!memcg_kmem_enabled())
71                 return NULL;
72         page = virt_to_head_page(ptr);
73         return page->mem_cgroup;
74 }
75
76 static inline struct list_lru_one *
77 list_lru_from_kmem(struct list_lru_node *nlru, void *ptr)
78 {
79         struct mem_cgroup *memcg;
80
81         if (!nlru->memcg_lrus)
82                 return &nlru->lru;
83
84         memcg = mem_cgroup_from_kmem(ptr);
85         if (!memcg)
86                 return &nlru->lru;
87
88         return list_lru_from_memcg_idx(nlru, memcg_cache_id(memcg));
89 }
90 #else
91 static inline bool list_lru_memcg_aware(struct list_lru *lru)
92 {
93         return false;
94 }
95
96 static inline struct list_lru_one *
97 list_lru_from_memcg_idx(struct list_lru_node *nlru, int idx)
98 {
99         return &nlru->lru;
100 }
101
102 static inline struct list_lru_one *
103 list_lru_from_kmem(struct list_lru_node *nlru, void *ptr)
104 {
105         return &nlru->lru;
106 }
107 #endif /* CONFIG_MEMCG && !CONFIG_SLOB */
108
109 bool list_lru_add(struct list_lru *lru, struct list_head *item)
110 {
111         int nid = page_to_nid(virt_to_page(item));
112         struct list_lru_node *nlru = &lru->node[nid];
113         struct list_lru_one *l;
114
115         spin_lock(&nlru->lock);
116         if (list_empty(item)) {
117                 l = list_lru_from_kmem(nlru, item);
118                 list_add_tail(item, &l->list);
119                 l->nr_items++;
120                 nlru->nr_items++;
121                 spin_unlock(&nlru->lock);
122                 return true;
123         }
124         spin_unlock(&nlru->lock);
125         return false;
126 }
127 EXPORT_SYMBOL_GPL(list_lru_add);
128
129 bool list_lru_del(struct list_lru *lru, struct list_head *item)
130 {
131         int nid = page_to_nid(virt_to_page(item));
132         struct list_lru_node *nlru = &lru->node[nid];
133         struct list_lru_one *l;
134
135         spin_lock(&nlru->lock);
136         if (!list_empty(item)) {
137                 l = list_lru_from_kmem(nlru, item);
138                 list_del_init(item);
139                 l->nr_items--;
140                 nlru->nr_items--;
141                 spin_unlock(&nlru->lock);
142                 return true;
143         }
144         spin_unlock(&nlru->lock);
145         return false;
146 }
147 EXPORT_SYMBOL_GPL(list_lru_del);
148
149 void list_lru_isolate(struct list_lru_one *list, struct list_head *item)
150 {
151         list_del_init(item);
152         list->nr_items--;
153 }
154 EXPORT_SYMBOL_GPL(list_lru_isolate);
155
156 void list_lru_isolate_move(struct list_lru_one *list, struct list_head *item,
157                            struct list_head *head)
158 {
159         list_move(item, head);
160         list->nr_items--;
161 }
162 EXPORT_SYMBOL_GPL(list_lru_isolate_move);
163
164 static unsigned long __list_lru_count_one(struct list_lru *lru,
165                                           int nid, int memcg_idx)
166 {
167         struct list_lru_node *nlru = &lru->node[nid];
168         struct list_lru_one *l;
169         unsigned long count;
170
171         spin_lock(&nlru->lock);
172         l = list_lru_from_memcg_idx(nlru, memcg_idx);
173         count = l->nr_items;
174         spin_unlock(&nlru->lock);
175
176         return count;
177 }
178
179 unsigned long list_lru_count_one(struct list_lru *lru,
180                                  int nid, struct mem_cgroup *memcg)
181 {
182         return __list_lru_count_one(lru, nid, memcg_cache_id(memcg));
183 }
184 EXPORT_SYMBOL_GPL(list_lru_count_one);
185
186 unsigned long list_lru_count_node(struct list_lru *lru, int nid)
187 {
188         struct list_lru_node *nlru;
189
190         nlru = &lru->node[nid];
191         return nlru->nr_items;
192 }
193 EXPORT_SYMBOL_GPL(list_lru_count_node);
194
195 static unsigned long
196 __list_lru_walk_one(struct list_lru *lru, int nid, int memcg_idx,
197                     list_lru_walk_cb isolate, void *cb_arg,
198                     unsigned long *nr_to_walk)
199 {
200
201         struct list_lru_node *nlru = &lru->node[nid];
202         struct list_lru_one *l;
203         struct list_head *item, *n;
204         unsigned long isolated = 0;
205
206         spin_lock(&nlru->lock);
207         l = list_lru_from_memcg_idx(nlru, memcg_idx);
208 restart:
209         list_for_each_safe(item, n, &l->list) {
210                 enum lru_status ret;
211
212                 /*
213                  * decrement nr_to_walk first so that we don't livelock if we
214                  * get stuck on large numbesr of LRU_RETRY items
215                  */
216                 if (!*nr_to_walk)
217                         break;
218                 --*nr_to_walk;
219
220                 ret = isolate(item, l, &nlru->lock, cb_arg);
221                 switch (ret) {
222                 case LRU_REMOVED_RETRY:
223                         assert_spin_locked(&nlru->lock);
224                         /* fall through */
225                 case LRU_REMOVED:
226                         isolated++;
227                         nlru->nr_items--;
228                         /*
229                          * If the lru lock has been dropped, our list
230                          * traversal is now invalid and so we have to
231                          * restart from scratch.
232                          */
233                         if (ret == LRU_REMOVED_RETRY)
234                                 goto restart;
235                         break;
236                 case LRU_ROTATE:
237                         list_move_tail(item, &l->list);
238                         break;
239                 case LRU_SKIP:
240                         break;
241                 case LRU_RETRY:
242                         /*
243                          * The lru lock has been dropped, our list traversal is
244                          * now invalid and so we have to restart from scratch.
245                          */
246                         assert_spin_locked(&nlru->lock);
247                         goto restart;
248                 default:
249                         BUG();
250                 }
251         }
252
253         spin_unlock(&nlru->lock);
254         return isolated;
255 }
256
257 unsigned long
258 list_lru_walk_one(struct list_lru *lru, int nid, struct mem_cgroup *memcg,
259                   list_lru_walk_cb isolate, void *cb_arg,
260                   unsigned long *nr_to_walk)
261 {
262         return __list_lru_walk_one(lru, nid, memcg_cache_id(memcg),
263                                    isolate, cb_arg, nr_to_walk);
264 }
265 EXPORT_SYMBOL_GPL(list_lru_walk_one);
266
267 unsigned long list_lru_walk_node(struct list_lru *lru, int nid,
268                                  list_lru_walk_cb isolate, void *cb_arg,
269                                  unsigned long *nr_to_walk)
270 {
271         long isolated = 0;
272         int memcg_idx;
273
274         isolated += __list_lru_walk_one(lru, nid, -1, isolate, cb_arg,
275                                         nr_to_walk);
276         if (*nr_to_walk > 0 && list_lru_memcg_aware(lru)) {
277                 for_each_memcg_cache_index(memcg_idx) {
278                         isolated += __list_lru_walk_one(lru, nid, memcg_idx,
279                                                 isolate, cb_arg, nr_to_walk);
280                         if (*nr_to_walk <= 0)
281                                 break;
282                 }
283         }
284         return isolated;
285 }
286 EXPORT_SYMBOL_GPL(list_lru_walk_node);
287
288 static void init_one_lru(struct list_lru_one *l)
289 {
290         INIT_LIST_HEAD(&l->list);
291         l->nr_items = 0;
292 }
293
294 #if defined(CONFIG_MEMCG) && !defined(CONFIG_SLOB)
295 static void __memcg_destroy_list_lru_node(struct list_lru_memcg *memcg_lrus,
296                                           int begin, int end)
297 {
298         int i;
299
300         for (i = begin; i < end; i++)
301                 kfree(memcg_lrus->lru[i]);
302 }
303
304 static int __memcg_init_list_lru_node(struct list_lru_memcg *memcg_lrus,
305                                       int begin, int end)
306 {
307         int i;
308
309         for (i = begin; i < end; i++) {
310                 struct list_lru_one *l;
311
312                 l = kmalloc(sizeof(struct list_lru_one), GFP_KERNEL);
313                 if (!l)
314                         goto fail;
315
316                 init_one_lru(l);
317                 memcg_lrus->lru[i] = l;
318         }
319         return 0;
320 fail:
321         __memcg_destroy_list_lru_node(memcg_lrus, begin, i - 1);
322         return -ENOMEM;
323 }
324
325 static int memcg_init_list_lru_node(struct list_lru_node *nlru)
326 {
327         int size = memcg_nr_cache_ids;
328
329         nlru->memcg_lrus = kvmalloc(size * sizeof(void *), GFP_KERNEL);
330         if (!nlru->memcg_lrus)
331                 return -ENOMEM;
332
333         if (__memcg_init_list_lru_node(nlru->memcg_lrus, 0, size)) {
334                 kvfree(nlru->memcg_lrus);
335                 return -ENOMEM;
336         }
337
338         return 0;
339 }
340
341 static void memcg_destroy_list_lru_node(struct list_lru_node *nlru)
342 {
343         __memcg_destroy_list_lru_node(nlru->memcg_lrus, 0, memcg_nr_cache_ids);
344         kvfree(nlru->memcg_lrus);
345 }
346
347 static int memcg_update_list_lru_node(struct list_lru_node *nlru,
348                                       int old_size, int new_size)
349 {
350         struct list_lru_memcg *old, *new;
351
352         BUG_ON(old_size > new_size);
353
354         old = nlru->memcg_lrus;
355         new = kvmalloc(new_size * sizeof(void *), GFP_KERNEL);
356         if (!new)
357                 return -ENOMEM;
358
359         if (__memcg_init_list_lru_node(new, old_size, new_size)) {
360                 kvfree(new);
361                 return -ENOMEM;
362         }
363
364         memcpy(new, old, old_size * sizeof(void *));
365
366         /*
367          * The lock guarantees that we won't race with a reader
368          * (see list_lru_from_memcg_idx).
369          *
370          * Since list_lru_{add,del} may be called under an IRQ-safe lock,
371          * we have to use IRQ-safe primitives here to avoid deadlock.
372          */
373         spin_lock_irq(&nlru->lock);
374         nlru->memcg_lrus = new;
375         spin_unlock_irq(&nlru->lock);
376
377         kvfree(old);
378         return 0;
379 }
380
381 static void memcg_cancel_update_list_lru_node(struct list_lru_node *nlru,
382                                               int old_size, int new_size)
383 {
384         /* do not bother shrinking the array back to the old size, because we
385          * cannot handle allocation failures here */
386         __memcg_destroy_list_lru_node(nlru->memcg_lrus, old_size, new_size);
387 }
388
389 static int memcg_init_list_lru(struct list_lru *lru, bool memcg_aware)
390 {
391         int i;
392
393         if (!memcg_aware)
394                 return 0;
395
396         for_each_node(i) {
397                 if (memcg_init_list_lru_node(&lru->node[i]))
398                         goto fail;
399         }
400         return 0;
401 fail:
402         for (i = i - 1; i >= 0; i--) {
403                 if (!lru->node[i].memcg_lrus)
404                         continue;
405                 memcg_destroy_list_lru_node(&lru->node[i]);
406         }
407         return -ENOMEM;
408 }
409
410 static void memcg_destroy_list_lru(struct list_lru *lru)
411 {
412         int i;
413
414         if (!list_lru_memcg_aware(lru))
415                 return;
416
417         for_each_node(i)
418                 memcg_destroy_list_lru_node(&lru->node[i]);
419 }
420
421 static int memcg_update_list_lru(struct list_lru *lru,
422                                  int old_size, int new_size)
423 {
424         int i;
425
426         if (!list_lru_memcg_aware(lru))
427                 return 0;
428
429         for_each_node(i) {
430                 if (memcg_update_list_lru_node(&lru->node[i],
431                                                old_size, new_size))
432                         goto fail;
433         }
434         return 0;
435 fail:
436         for (i = i - 1; i >= 0; i--) {
437                 if (!lru->node[i].memcg_lrus)
438                         continue;
439
440                 memcg_cancel_update_list_lru_node(&lru->node[i],
441                                                   old_size, new_size);
442         }
443         return -ENOMEM;
444 }
445
446 static void memcg_cancel_update_list_lru(struct list_lru *lru,
447                                          int old_size, int new_size)
448 {
449         int i;
450
451         if (!list_lru_memcg_aware(lru))
452                 return;
453
454         for_each_node(i)
455                 memcg_cancel_update_list_lru_node(&lru->node[i],
456                                                   old_size, new_size);
457 }
458
459 int memcg_update_all_list_lrus(int new_size)
460 {
461         int ret = 0;
462         struct list_lru *lru;
463         int old_size = memcg_nr_cache_ids;
464
465         mutex_lock(&list_lrus_mutex);
466         list_for_each_entry(lru, &list_lrus, list) {
467                 ret = memcg_update_list_lru(lru, old_size, new_size);
468                 if (ret)
469                         goto fail;
470         }
471 out:
472         mutex_unlock(&list_lrus_mutex);
473         return ret;
474 fail:
475         list_for_each_entry_continue_reverse(lru, &list_lrus, list)
476                 memcg_cancel_update_list_lru(lru, old_size, new_size);
477         goto out;
478 }
479
480 static void memcg_drain_list_lru_node(struct list_lru_node *nlru,
481                                       int src_idx, int dst_idx)
482 {
483         struct list_lru_one *src, *dst;
484
485         /*
486          * Since list_lru_{add,del} may be called under an IRQ-safe lock,
487          * we have to use IRQ-safe primitives here to avoid deadlock.
488          */
489         spin_lock_irq(&nlru->lock);
490
491         src = list_lru_from_memcg_idx(nlru, src_idx);
492         dst = list_lru_from_memcg_idx(nlru, dst_idx);
493
494         list_splice_init(&src->list, &dst->list);
495         dst->nr_items += src->nr_items;
496         src->nr_items = 0;
497
498         spin_unlock_irq(&nlru->lock);
499 }
500
501 static void memcg_drain_list_lru(struct list_lru *lru,
502                                  int src_idx, int dst_idx)
503 {
504         int i;
505
506         if (!list_lru_memcg_aware(lru))
507                 return;
508
509         for_each_node(i)
510                 memcg_drain_list_lru_node(&lru->node[i], src_idx, dst_idx);
511 }
512
513 void memcg_drain_all_list_lrus(int src_idx, int dst_idx)
514 {
515         struct list_lru *lru;
516
517         mutex_lock(&list_lrus_mutex);
518         list_for_each_entry(lru, &list_lrus, list)
519                 memcg_drain_list_lru(lru, src_idx, dst_idx);
520         mutex_unlock(&list_lrus_mutex);
521 }
522 #else
523 static int memcg_init_list_lru(struct list_lru *lru, bool memcg_aware)
524 {
525         return 0;
526 }
527
528 static void memcg_destroy_list_lru(struct list_lru *lru)
529 {
530 }
531 #endif /* CONFIG_MEMCG && !CONFIG_SLOB */
532
533 int __list_lru_init(struct list_lru *lru, bool memcg_aware,
534                     struct lock_class_key *key)
535 {
536         int i;
537         size_t size = sizeof(*lru->node) * nr_node_ids;
538         int err = -ENOMEM;
539
540         memcg_get_cache_ids();
541
542         lru->node = kzalloc(size, GFP_KERNEL);
543         if (!lru->node)
544                 goto out;
545
546         for_each_node(i) {
547                 spin_lock_init(&lru->node[i].lock);
548                 if (key)
549                         lockdep_set_class(&lru->node[i].lock, key);
550                 init_one_lru(&lru->node[i].lru);
551         }
552
553         err = memcg_init_list_lru(lru, memcg_aware);
554         if (err) {
555                 kfree(lru->node);
556                 /* Do this so a list_lru_destroy() doesn't crash: */
557                 lru->node = NULL;
558                 goto out;
559         }
560
561         list_lru_register(lru);
562 out:
563         memcg_put_cache_ids();
564         return err;
565 }
566 EXPORT_SYMBOL_GPL(__list_lru_init);
567
568 void list_lru_destroy(struct list_lru *lru)
569 {
570         /* Already destroyed or not yet initialized? */
571         if (!lru->node)
572                 return;
573
574         memcg_get_cache_ids();
575
576         list_lru_unregister(lru);
577
578         memcg_destroy_list_lru(lru);
579         kfree(lru->node);
580         lru->node = NULL;
581
582         memcg_put_cache_ids();
583 }
584 EXPORT_SYMBOL_GPL(list_lru_destroy);