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8cdea7c0 BS |
1 | /* memcontrol.c - Memory Controller |
2 | * | |
3 | * Copyright IBM Corporation, 2007 | |
4 | * Author Balbir Singh <balbir@linux.vnet.ibm.com> | |
5 | * | |
78fb7466 PE |
6 | * Copyright 2007 OpenVZ SWsoft Inc |
7 | * Author: Pavel Emelianov <xemul@openvz.org> | |
8 | * | |
8cdea7c0 BS |
9 | * This program is free software; you can redistribute it and/or modify |
10 | * it under the terms of the GNU General Public License as published by | |
11 | * the Free Software Foundation; either version 2 of the License, or | |
12 | * (at your option) any later version. | |
13 | * | |
14 | * This program is distributed in the hope that it will be useful, | |
15 | * but WITHOUT ANY WARRANTY; without even the implied warranty of | |
16 | * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
17 | * GNU General Public License for more details. | |
18 | */ | |
19 | ||
20 | #include <linux/res_counter.h> | |
21 | #include <linux/memcontrol.h> | |
22 | #include <linux/cgroup.h> | |
78fb7466 | 23 | #include <linux/mm.h> |
8a9f3ccd | 24 | #include <linux/page-flags.h> |
66e1707b | 25 | #include <linux/backing-dev.h> |
8a9f3ccd BS |
26 | #include <linux/bit_spinlock.h> |
27 | #include <linux/rcupdate.h> | |
66e1707b BS |
28 | #include <linux/swap.h> |
29 | #include <linux/spinlock.h> | |
30 | #include <linux/fs.h> | |
8cdea7c0 BS |
31 | |
32 | struct cgroup_subsys mem_cgroup_subsys; | |
66e1707b | 33 | static const int MEM_CGROUP_RECLAIM_RETRIES = 5; |
8cdea7c0 BS |
34 | |
35 | /* | |
36 | * The memory controller data structure. The memory controller controls both | |
37 | * page cache and RSS per cgroup. We would eventually like to provide | |
38 | * statistics based on the statistics developed by Rik Van Riel for clock-pro, | |
39 | * to help the administrator determine what knobs to tune. | |
40 | * | |
41 | * TODO: Add a water mark for the memory controller. Reclaim will begin when | |
8a9f3ccd BS |
42 | * we hit the water mark. May be even add a low water mark, such that |
43 | * no reclaim occurs from a cgroup at it's low water mark, this is | |
44 | * a feature that will be implemented much later in the future. | |
8cdea7c0 BS |
45 | */ |
46 | struct mem_cgroup { | |
47 | struct cgroup_subsys_state css; | |
48 | /* | |
49 | * the counter to account for memory usage | |
50 | */ | |
51 | struct res_counter res; | |
78fb7466 PE |
52 | /* |
53 | * Per cgroup active and inactive list, similar to the | |
54 | * per zone LRU lists. | |
55 | * TODO: Consider making these lists per zone | |
56 | */ | |
57 | struct list_head active_list; | |
58 | struct list_head inactive_list; | |
66e1707b BS |
59 | /* |
60 | * spin_lock to protect the per cgroup LRU | |
61 | */ | |
62 | spinlock_t lru_lock; | |
8cdea7c0 BS |
63 | }; |
64 | ||
8a9f3ccd BS |
65 | /* |
66 | * We use the lower bit of the page->page_cgroup pointer as a bit spin | |
67 | * lock. We need to ensure that page->page_cgroup is atleast two | |
68 | * byte aligned (based on comments from Nick Piggin) | |
69 | */ | |
70 | #define PAGE_CGROUP_LOCK_BIT 0x0 | |
71 | #define PAGE_CGROUP_LOCK (1 << PAGE_CGROUP_LOCK_BIT) | |
72 | ||
8cdea7c0 BS |
73 | /* |
74 | * A page_cgroup page is associated with every page descriptor. The | |
75 | * page_cgroup helps us identify information about the cgroup | |
76 | */ | |
77 | struct page_cgroup { | |
78 | struct list_head lru; /* per cgroup LRU list */ | |
79 | struct page *page; | |
80 | struct mem_cgroup *mem_cgroup; | |
8a9f3ccd BS |
81 | atomic_t ref_cnt; /* Helpful when pages move b/w */ |
82 | /* mapped and cached states */ | |
8cdea7c0 BS |
83 | }; |
84 | ||
85 | ||
86 | static inline | |
87 | struct mem_cgroup *mem_cgroup_from_cont(struct cgroup *cont) | |
88 | { | |
89 | return container_of(cgroup_subsys_state(cont, | |
90 | mem_cgroup_subsys_id), struct mem_cgroup, | |
91 | css); | |
92 | } | |
93 | ||
78fb7466 PE |
94 | static inline |
95 | struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p) | |
96 | { | |
97 | return container_of(task_subsys_state(p, mem_cgroup_subsys_id), | |
98 | struct mem_cgroup, css); | |
99 | } | |
100 | ||
101 | void mm_init_cgroup(struct mm_struct *mm, struct task_struct *p) | |
102 | { | |
103 | struct mem_cgroup *mem; | |
104 | ||
105 | mem = mem_cgroup_from_task(p); | |
106 | css_get(&mem->css); | |
107 | mm->mem_cgroup = mem; | |
108 | } | |
109 | ||
110 | void mm_free_cgroup(struct mm_struct *mm) | |
111 | { | |
112 | css_put(&mm->mem_cgroup->css); | |
113 | } | |
114 | ||
8a9f3ccd BS |
115 | static inline int page_cgroup_locked(struct page *page) |
116 | { | |
117 | return bit_spin_is_locked(PAGE_CGROUP_LOCK_BIT, | |
118 | &page->page_cgroup); | |
119 | } | |
120 | ||
78fb7466 PE |
121 | void page_assign_page_cgroup(struct page *page, struct page_cgroup *pc) |
122 | { | |
8a9f3ccd BS |
123 | int locked; |
124 | ||
125 | /* | |
126 | * While resetting the page_cgroup we might not hold the | |
127 | * page_cgroup lock. free_hot_cold_page() is an example | |
128 | * of such a scenario | |
129 | */ | |
130 | if (pc) | |
131 | VM_BUG_ON(!page_cgroup_locked(page)); | |
132 | locked = (page->page_cgroup & PAGE_CGROUP_LOCK); | |
133 | page->page_cgroup = ((unsigned long)pc | locked); | |
78fb7466 PE |
134 | } |
135 | ||
136 | struct page_cgroup *page_get_page_cgroup(struct page *page) | |
137 | { | |
8a9f3ccd BS |
138 | return (struct page_cgroup *) |
139 | (page->page_cgroup & ~PAGE_CGROUP_LOCK); | |
140 | } | |
141 | ||
142 | void __always_inline lock_page_cgroup(struct page *page) | |
143 | { | |
144 | bit_spin_lock(PAGE_CGROUP_LOCK_BIT, &page->page_cgroup); | |
145 | VM_BUG_ON(!page_cgroup_locked(page)); | |
146 | } | |
147 | ||
148 | void __always_inline unlock_page_cgroup(struct page *page) | |
149 | { | |
150 | bit_spin_unlock(PAGE_CGROUP_LOCK_BIT, &page->page_cgroup); | |
151 | } | |
152 | ||
66e1707b BS |
153 | void __mem_cgroup_move_lists(struct page_cgroup *pc, bool active) |
154 | { | |
155 | if (active) | |
156 | list_move(&pc->lru, &pc->mem_cgroup->active_list); | |
157 | else | |
158 | list_move(&pc->lru, &pc->mem_cgroup->inactive_list); | |
159 | } | |
160 | ||
161 | /* | |
162 | * This routine assumes that the appropriate zone's lru lock is already held | |
163 | */ | |
164 | void mem_cgroup_move_lists(struct page_cgroup *pc, bool active) | |
165 | { | |
166 | struct mem_cgroup *mem; | |
167 | if (!pc) | |
168 | return; | |
169 | ||
170 | mem = pc->mem_cgroup; | |
171 | ||
172 | spin_lock(&mem->lru_lock); | |
173 | __mem_cgroup_move_lists(pc, active); | |
174 | spin_unlock(&mem->lru_lock); | |
175 | } | |
176 | ||
177 | unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan, | |
178 | struct list_head *dst, | |
179 | unsigned long *scanned, int order, | |
180 | int mode, struct zone *z, | |
181 | struct mem_cgroup *mem_cont, | |
182 | int active) | |
183 | { | |
184 | unsigned long nr_taken = 0; | |
185 | struct page *page; | |
186 | unsigned long scan; | |
187 | LIST_HEAD(pc_list); | |
188 | struct list_head *src; | |
189 | struct page_cgroup *pc; | |
190 | ||
191 | if (active) | |
192 | src = &mem_cont->active_list; | |
193 | else | |
194 | src = &mem_cont->inactive_list; | |
195 | ||
196 | spin_lock(&mem_cont->lru_lock); | |
197 | for (scan = 0; scan < nr_to_scan && !list_empty(src); scan++) { | |
198 | pc = list_entry(src->prev, struct page_cgroup, lru); | |
199 | page = pc->page; | |
200 | VM_BUG_ON(!pc); | |
201 | ||
202 | if (PageActive(page) && !active) { | |
203 | __mem_cgroup_move_lists(pc, true); | |
204 | scan--; | |
205 | continue; | |
206 | } | |
207 | if (!PageActive(page) && active) { | |
208 | __mem_cgroup_move_lists(pc, false); | |
209 | scan--; | |
210 | continue; | |
211 | } | |
212 | ||
213 | /* | |
214 | * Reclaim, per zone | |
215 | * TODO: make the active/inactive lists per zone | |
216 | */ | |
217 | if (page_zone(page) != z) | |
218 | continue; | |
219 | ||
220 | /* | |
221 | * Check if the meta page went away from under us | |
222 | */ | |
223 | if (!list_empty(&pc->lru)) | |
224 | list_move(&pc->lru, &pc_list); | |
225 | else | |
226 | continue; | |
227 | ||
228 | if (__isolate_lru_page(page, mode) == 0) { | |
229 | list_move(&page->lru, dst); | |
230 | nr_taken++; | |
231 | } | |
232 | } | |
233 | ||
234 | list_splice(&pc_list, src); | |
235 | spin_unlock(&mem_cont->lru_lock); | |
236 | ||
237 | *scanned = scan; | |
238 | return nr_taken; | |
239 | } | |
240 | ||
8a9f3ccd BS |
241 | /* |
242 | * Charge the memory controller for page usage. | |
243 | * Return | |
244 | * 0 if the charge was successful | |
245 | * < 0 if the cgroup is over its limit | |
246 | */ | |
247 | int mem_cgroup_charge(struct page *page, struct mm_struct *mm) | |
248 | { | |
249 | struct mem_cgroup *mem; | |
250 | struct page_cgroup *pc, *race_pc; | |
66e1707b BS |
251 | unsigned long flags; |
252 | unsigned long nr_retries = MEM_CGROUP_RECLAIM_RETRIES; | |
8a9f3ccd BS |
253 | |
254 | /* | |
255 | * Should page_cgroup's go to their own slab? | |
256 | * One could optimize the performance of the charging routine | |
257 | * by saving a bit in the page_flags and using it as a lock | |
258 | * to see if the cgroup page already has a page_cgroup associated | |
259 | * with it | |
260 | */ | |
66e1707b | 261 | retry: |
8a9f3ccd BS |
262 | lock_page_cgroup(page); |
263 | pc = page_get_page_cgroup(page); | |
264 | /* | |
265 | * The page_cgroup exists and the page has already been accounted | |
266 | */ | |
267 | if (pc) { | |
66e1707b BS |
268 | if (unlikely(!atomic_inc_not_zero(&pc->ref_cnt))) { |
269 | /* this page is under being uncharged ? */ | |
270 | unlock_page_cgroup(page); | |
271 | cpu_relax(); | |
272 | goto retry; | |
273 | } else | |
274 | goto done; | |
8a9f3ccd BS |
275 | } |
276 | ||
277 | unlock_page_cgroup(page); | |
278 | ||
279 | pc = kzalloc(sizeof(struct page_cgroup), GFP_KERNEL); | |
280 | if (pc == NULL) | |
281 | goto err; | |
282 | ||
283 | rcu_read_lock(); | |
284 | /* | |
285 | * We always charge the cgroup the mm_struct belongs to | |
286 | * the mm_struct's mem_cgroup changes on task migration if the | |
287 | * thread group leader migrates. It's possible that mm is not | |
288 | * set, if so charge the init_mm (happens for pagecache usage). | |
289 | */ | |
290 | if (!mm) | |
291 | mm = &init_mm; | |
292 | ||
293 | mem = rcu_dereference(mm->mem_cgroup); | |
294 | /* | |
295 | * For every charge from the cgroup, increment reference | |
296 | * count | |
297 | */ | |
298 | css_get(&mem->css); | |
299 | rcu_read_unlock(); | |
300 | ||
301 | /* | |
302 | * If we created the page_cgroup, we should free it on exceeding | |
303 | * the cgroup limit. | |
304 | */ | |
66e1707b BS |
305 | while (res_counter_charge(&mem->res, 1)) { |
306 | if (try_to_free_mem_cgroup_pages(mem)) | |
307 | continue; | |
308 | ||
309 | /* | |
310 | * try_to_free_mem_cgroup_pages() might not give us a full | |
311 | * picture of reclaim. Some pages are reclaimed and might be | |
312 | * moved to swap cache or just unmapped from the cgroup. | |
313 | * Check the limit again to see if the reclaim reduced the | |
314 | * current usage of the cgroup before giving up | |
315 | */ | |
316 | if (res_counter_check_under_limit(&mem->res)) | |
317 | continue; | |
318 | /* | |
319 | * Since we control both RSS and cache, we end up with a | |
320 | * very interesting scenario where we end up reclaiming | |
321 | * memory (essentially RSS), since the memory is pushed | |
322 | * to swap cache, we eventually end up adding those | |
323 | * pages back to our list. Hence we give ourselves a | |
324 | * few chances before we fail | |
325 | */ | |
326 | else if (nr_retries--) { | |
327 | congestion_wait(WRITE, HZ/10); | |
328 | continue; | |
329 | } | |
330 | ||
8a9f3ccd BS |
331 | css_put(&mem->css); |
332 | goto free_pc; | |
333 | } | |
334 | ||
335 | lock_page_cgroup(page); | |
336 | /* | |
337 | * Check if somebody else beat us to allocating the page_cgroup | |
338 | */ | |
339 | race_pc = page_get_page_cgroup(page); | |
340 | if (race_pc) { | |
341 | kfree(pc); | |
342 | pc = race_pc; | |
343 | atomic_inc(&pc->ref_cnt); | |
344 | res_counter_uncharge(&mem->res, 1); | |
345 | css_put(&mem->css); | |
346 | goto done; | |
347 | } | |
348 | ||
349 | atomic_set(&pc->ref_cnt, 1); | |
350 | pc->mem_cgroup = mem; | |
351 | pc->page = page; | |
352 | page_assign_page_cgroup(page, pc); | |
353 | ||
66e1707b BS |
354 | spin_lock_irqsave(&mem->lru_lock, flags); |
355 | list_add(&pc->lru, &mem->active_list); | |
356 | spin_unlock_irqrestore(&mem->lru_lock, flags); | |
357 | ||
8a9f3ccd BS |
358 | done: |
359 | unlock_page_cgroup(page); | |
360 | return 0; | |
361 | free_pc: | |
362 | kfree(pc); | |
8a9f3ccd | 363 | err: |
8a9f3ccd BS |
364 | return -ENOMEM; |
365 | } | |
366 | ||
367 | /* | |
368 | * Uncharging is always a welcome operation, we never complain, simply | |
369 | * uncharge. | |
370 | */ | |
371 | void mem_cgroup_uncharge(struct page_cgroup *pc) | |
372 | { | |
373 | struct mem_cgroup *mem; | |
374 | struct page *page; | |
66e1707b | 375 | unsigned long flags; |
8a9f3ccd BS |
376 | |
377 | if (!pc) | |
378 | return; | |
379 | ||
380 | if (atomic_dec_and_test(&pc->ref_cnt)) { | |
381 | page = pc->page; | |
382 | lock_page_cgroup(page); | |
383 | mem = pc->mem_cgroup; | |
384 | css_put(&mem->css); | |
385 | page_assign_page_cgroup(page, NULL); | |
386 | unlock_page_cgroup(page); | |
387 | res_counter_uncharge(&mem->res, 1); | |
66e1707b BS |
388 | |
389 | spin_lock_irqsave(&mem->lru_lock, flags); | |
390 | list_del_init(&pc->lru); | |
391 | spin_unlock_irqrestore(&mem->lru_lock, flags); | |
8a9f3ccd BS |
392 | kfree(pc); |
393 | } | |
78fb7466 PE |
394 | } |
395 | ||
8cdea7c0 BS |
396 | static ssize_t mem_cgroup_read(struct cgroup *cont, struct cftype *cft, |
397 | struct file *file, char __user *userbuf, size_t nbytes, | |
398 | loff_t *ppos) | |
399 | { | |
400 | return res_counter_read(&mem_cgroup_from_cont(cont)->res, | |
401 | cft->private, userbuf, nbytes, ppos); | |
402 | } | |
403 | ||
404 | static ssize_t mem_cgroup_write(struct cgroup *cont, struct cftype *cft, | |
405 | struct file *file, const char __user *userbuf, | |
406 | size_t nbytes, loff_t *ppos) | |
407 | { | |
408 | return res_counter_write(&mem_cgroup_from_cont(cont)->res, | |
409 | cft->private, userbuf, nbytes, ppos); | |
410 | } | |
411 | ||
412 | static struct cftype mem_cgroup_files[] = { | |
413 | { | |
414 | .name = "usage", | |
415 | .private = RES_USAGE, | |
416 | .read = mem_cgroup_read, | |
417 | }, | |
418 | { | |
419 | .name = "limit", | |
420 | .private = RES_LIMIT, | |
421 | .write = mem_cgroup_write, | |
422 | .read = mem_cgroup_read, | |
423 | }, | |
424 | { | |
425 | .name = "failcnt", | |
426 | .private = RES_FAILCNT, | |
427 | .read = mem_cgroup_read, | |
428 | }, | |
429 | }; | |
430 | ||
78fb7466 PE |
431 | static struct mem_cgroup init_mem_cgroup; |
432 | ||
8cdea7c0 BS |
433 | static struct cgroup_subsys_state * |
434 | mem_cgroup_create(struct cgroup_subsys *ss, struct cgroup *cont) | |
435 | { | |
436 | struct mem_cgroup *mem; | |
437 | ||
78fb7466 PE |
438 | if (unlikely((cont->parent) == NULL)) { |
439 | mem = &init_mem_cgroup; | |
440 | init_mm.mem_cgroup = mem; | |
441 | } else | |
442 | mem = kzalloc(sizeof(struct mem_cgroup), GFP_KERNEL); | |
443 | ||
444 | if (mem == NULL) | |
445 | return NULL; | |
8cdea7c0 BS |
446 | |
447 | res_counter_init(&mem->res); | |
8a9f3ccd BS |
448 | INIT_LIST_HEAD(&mem->active_list); |
449 | INIT_LIST_HEAD(&mem->inactive_list); | |
66e1707b | 450 | spin_lock_init(&mem->lru_lock); |
8cdea7c0 BS |
451 | return &mem->css; |
452 | } | |
453 | ||
454 | static void mem_cgroup_destroy(struct cgroup_subsys *ss, | |
455 | struct cgroup *cont) | |
456 | { | |
457 | kfree(mem_cgroup_from_cont(cont)); | |
458 | } | |
459 | ||
460 | static int mem_cgroup_populate(struct cgroup_subsys *ss, | |
461 | struct cgroup *cont) | |
462 | { | |
463 | return cgroup_add_files(cont, ss, mem_cgroup_files, | |
464 | ARRAY_SIZE(mem_cgroup_files)); | |
465 | } | |
466 | ||
67e465a7 BS |
467 | static void mem_cgroup_move_task(struct cgroup_subsys *ss, |
468 | struct cgroup *cont, | |
469 | struct cgroup *old_cont, | |
470 | struct task_struct *p) | |
471 | { | |
472 | struct mm_struct *mm; | |
473 | struct mem_cgroup *mem, *old_mem; | |
474 | ||
475 | mm = get_task_mm(p); | |
476 | if (mm == NULL) | |
477 | return; | |
478 | ||
479 | mem = mem_cgroup_from_cont(cont); | |
480 | old_mem = mem_cgroup_from_cont(old_cont); | |
481 | ||
482 | if (mem == old_mem) | |
483 | goto out; | |
484 | ||
485 | /* | |
486 | * Only thread group leaders are allowed to migrate, the mm_struct is | |
487 | * in effect owned by the leader | |
488 | */ | |
489 | if (p->tgid != p->pid) | |
490 | goto out; | |
491 | ||
492 | css_get(&mem->css); | |
493 | rcu_assign_pointer(mm->mem_cgroup, mem); | |
494 | css_put(&old_mem->css); | |
495 | ||
496 | out: | |
497 | mmput(mm); | |
498 | return; | |
499 | } | |
500 | ||
8cdea7c0 BS |
501 | struct cgroup_subsys mem_cgroup_subsys = { |
502 | .name = "memory", | |
503 | .subsys_id = mem_cgroup_subsys_id, | |
504 | .create = mem_cgroup_create, | |
505 | .destroy = mem_cgroup_destroy, | |
506 | .populate = mem_cgroup_populate, | |
67e465a7 | 507 | .attach = mem_cgroup_move_task, |
78fb7466 | 508 | .early_init = 1, |
8cdea7c0 | 509 | }; |