xref: /openbmc/linux/mm/hugetlb_cgroup.c (revision 015d239a) 
1 /*
2  *
3  * Copyright IBM Corporation, 2012
4  * Author Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
5  *
6  * Cgroup v2
7  * Copyright (C) 2019 Red Hat, Inc.
8  * Author: Giuseppe Scrivano <gscrivan@redhat.com>
9  *
10  * This program is free software; you can redistribute it and/or modify it
11  * under the terms of version 2.1 of the GNU Lesser General Public License
12  * as published by the Free Software Foundation.
13  *
14  * This program is distributed in the hope that it would be useful, but
15  * WITHOUT ANY WARRANTY; without even the implied warranty of
16  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
17  *
18  */
19 
20 #include <linux/cgroup.h>
21 #include <linux/page_counter.h>
22 #include <linux/slab.h>
23 #include <linux/hugetlb.h>
24 #include <linux/hugetlb_cgroup.h>
25 
26 enum hugetlb_memory_event {
27 	HUGETLB_MAX,
28 	HUGETLB_NR_MEMORY_EVENTS,
29 };
30 
31 struct hugetlb_cgroup {
32 	struct cgroup_subsys_state css;
33 
34 	/*
35 	 * the counter to account for hugepages from hugetlb.
36 	 */
37 	struct page_counter hugepage[HUGE_MAX_HSTATE];
38 
39 	atomic_long_t events[HUGE_MAX_HSTATE][HUGETLB_NR_MEMORY_EVENTS];
40 	atomic_long_t events_local[HUGE_MAX_HSTATE][HUGETLB_NR_MEMORY_EVENTS];
41 
42 	/* Handle for "hugetlb.events" */
43 	struct cgroup_file events_file[HUGE_MAX_HSTATE];
44 
45 	/* Handle for "hugetlb.events.local" */
46 	struct cgroup_file events_local_file[HUGE_MAX_HSTATE];
47 };
48 
49 #define MEMFILE_PRIVATE(x, val)	(((x) << 16) | (val))
50 #define MEMFILE_IDX(val)	(((val) >> 16) & 0xffff)
51 #define MEMFILE_ATTR(val)	((val) & 0xffff)
52 
53 #define hugetlb_cgroup_from_counter(counter, idx)                   \
54 	container_of(counter, struct hugetlb_cgroup, hugepage[idx])
55 
56 static struct hugetlb_cgroup *root_h_cgroup __read_mostly;
57 
58 static inline
59 struct hugetlb_cgroup *hugetlb_cgroup_from_css(struct cgroup_subsys_state *s)
60 {
61 	return s ? container_of(s, struct hugetlb_cgroup, css) : NULL;
62 }
63 
64 static inline
65 struct hugetlb_cgroup *hugetlb_cgroup_from_task(struct task_struct *task)
66 {
67 	return hugetlb_cgroup_from_css(task_css(task, hugetlb_cgrp_id));
68 }
69 
70 static inline bool hugetlb_cgroup_is_root(struct hugetlb_cgroup *h_cg)
71 {
72 	return (h_cg == root_h_cgroup);
73 }
74 
75 static inline struct hugetlb_cgroup *
76 parent_hugetlb_cgroup(struct hugetlb_cgroup *h_cg)
77 {
78 	return hugetlb_cgroup_from_css(h_cg->css.parent);
79 }
80 
81 static inline bool hugetlb_cgroup_have_usage(struct hugetlb_cgroup *h_cg)
82 {
83 	int idx;
84 
85 	for (idx = 0; idx < hugetlb_max_hstate; idx++) {
86 		if (page_counter_read(&h_cg->hugepage[idx]))
87 			return true;
88 	}
89 	return false;
90 }
91 
92 static void hugetlb_cgroup_init(struct hugetlb_cgroup *h_cgroup,
93 				struct hugetlb_cgroup *parent_h_cgroup)
94 {
95 	int idx;
96 
97 	for (idx = 0; idx < HUGE_MAX_HSTATE; idx++) {
98 		struct page_counter *counter = &h_cgroup->hugepage[idx];
99 		struct page_counter *parent = NULL;
100 		unsigned long limit;
101 		int ret;
102 
103 		if (parent_h_cgroup)
104 			parent = &parent_h_cgroup->hugepage[idx];
105 		page_counter_init(counter, parent);
106 
107 		limit = round_down(PAGE_COUNTER_MAX,
108 				   1 << huge_page_order(&hstates[idx]));
109 		ret = page_counter_set_max(counter, limit);
110 		VM_BUG_ON(ret);
111 	}
112 }
113 
114 static struct cgroup_subsys_state *
115 hugetlb_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
116 {
117 	struct hugetlb_cgroup *parent_h_cgroup = hugetlb_cgroup_from_css(parent_css);
118 	struct hugetlb_cgroup *h_cgroup;
119 
120 	h_cgroup = kzalloc(sizeof(*h_cgroup), GFP_KERNEL);
121 	if (!h_cgroup)
122 		return ERR_PTR(-ENOMEM);
123 
124 	if (!parent_h_cgroup)
125 		root_h_cgroup = h_cgroup;
126 
127 	hugetlb_cgroup_init(h_cgroup, parent_h_cgroup);
128 	return &h_cgroup->css;
129 }
130 
131 static void hugetlb_cgroup_css_free(struct cgroup_subsys_state *css)
132 {
133 	struct hugetlb_cgroup *h_cgroup;
134 
135 	h_cgroup = hugetlb_cgroup_from_css(css);
136 	kfree(h_cgroup);
137 }
138 
139 
140 /*
141  * Should be called with hugetlb_lock held.
142  * Since we are holding hugetlb_lock, pages cannot get moved from
143  * active list or uncharged from the cgroup, So no need to get
144  * page reference and test for page active here. This function
145  * cannot fail.
146  */
147 static void hugetlb_cgroup_move_parent(int idx, struct hugetlb_cgroup *h_cg,
148 				       struct page *page)
149 {
150 	unsigned int nr_pages;
151 	struct page_counter *counter;
152 	struct hugetlb_cgroup *page_hcg;
153 	struct hugetlb_cgroup *parent = parent_hugetlb_cgroup(h_cg);
154 
155 	page_hcg = hugetlb_cgroup_from_page(page);
156 	/*
157 	 * We can have pages in active list without any cgroup
158 	 * ie, hugepage with less than 3 pages. We can safely
159 	 * ignore those pages.
160 	 */
161 	if (!page_hcg || page_hcg != h_cg)
162 		goto out;
163 
164 	nr_pages = compound_nr(page);
165 	if (!parent) {
166 		parent = root_h_cgroup;
167 		/* root has no limit */
168 		page_counter_charge(&parent->hugepage[idx], nr_pages);
169 	}
170 	counter = &h_cg->hugepage[idx];
171 	/* Take the pages off the local counter */
172 	page_counter_cancel(counter, nr_pages);
173 
174 	set_hugetlb_cgroup(page, parent);
175 out:
176 	return;
177 }
178 
179 /*
180  * Force the hugetlb cgroup to empty the hugetlb resources by moving them to
181  * the parent cgroup.
182  */
183 static void hugetlb_cgroup_css_offline(struct cgroup_subsys_state *css)
184 {
185 	struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_css(css);
186 	struct hstate *h;
187 	struct page *page;
188 	int idx = 0;
189 
190 	do {
191 		for_each_hstate(h) {
192 			spin_lock(&hugetlb_lock);
193 			list_for_each_entry(page, &h->hugepage_activelist, lru)
194 				hugetlb_cgroup_move_parent(idx, h_cg, page);
195 
196 			spin_unlock(&hugetlb_lock);
197 			idx++;
198 		}
199 		cond_resched();
200 	} while (hugetlb_cgroup_have_usage(h_cg));
201 }
202 
203 static inline void hugetlb_event(struct hugetlb_cgroup *hugetlb, int idx,
204 				 enum hugetlb_memory_event event)
205 {
206 	atomic_long_inc(&hugetlb->events_local[idx][event]);
207 	cgroup_file_notify(&hugetlb->events_local_file[idx]);
208 
209 	do {
210 		atomic_long_inc(&hugetlb->events[idx][event]);
211 		cgroup_file_notify(&hugetlb->events_file[idx]);
212 	} while ((hugetlb = parent_hugetlb_cgroup(hugetlb)) &&
213 		 !hugetlb_cgroup_is_root(hugetlb));
214 }
215 
216 int hugetlb_cgroup_charge_cgroup(int idx, unsigned long nr_pages,
217 				 struct hugetlb_cgroup **ptr)
218 {
219 	int ret = 0;
220 	struct page_counter *counter;
221 	struct hugetlb_cgroup *h_cg = NULL;
222 
223 	if (hugetlb_cgroup_disabled())
224 		goto done;
225 	/*
226 	 * We don't charge any cgroup if the compound page have less
227 	 * than 3 pages.
228 	 */
229 	if (huge_page_order(&hstates[idx]) < HUGETLB_CGROUP_MIN_ORDER)
230 		goto done;
231 again:
232 	rcu_read_lock();
233 	h_cg = hugetlb_cgroup_from_task(current);
234 	if (!css_tryget(&h_cg->css)) {
235 		rcu_read_unlock();
236 		goto again;
237 	}
238 	rcu_read_unlock();
239 
240 	if (!page_counter_try_charge(&h_cg->hugepage[idx], nr_pages,
241 				     &counter)) {
242 		ret = -ENOMEM;
243 		hugetlb_event(hugetlb_cgroup_from_counter(counter, idx), idx,
244 			      HUGETLB_MAX);
245 	}
246 	css_put(&h_cg->css);
247 done:
248 	*ptr = h_cg;
249 	return ret;
250 }
251 
252 /* Should be called with hugetlb_lock held */
253 void hugetlb_cgroup_commit_charge(int idx, unsigned long nr_pages,
254 				  struct hugetlb_cgroup *h_cg,
255 				  struct page *page)
256 {
257 	if (hugetlb_cgroup_disabled() || !h_cg)
258 		return;
259 
260 	set_hugetlb_cgroup(page, h_cg);
261 	return;
262 }
263 
264 /*
265  * Should be called with hugetlb_lock held
266  */
267 void hugetlb_cgroup_uncharge_page(int idx, unsigned long nr_pages,
268 				  struct page *page)
269 {
270 	struct hugetlb_cgroup *h_cg;
271 
272 	if (hugetlb_cgroup_disabled())
273 		return;
274 	lockdep_assert_held(&hugetlb_lock);
275 	h_cg = hugetlb_cgroup_from_page(page);
276 	if (unlikely(!h_cg))
277 		return;
278 	set_hugetlb_cgroup(page, NULL);
279 	page_counter_uncharge(&h_cg->hugepage[idx], nr_pages);
280 	return;
281 }
282 
283 void hugetlb_cgroup_uncharge_cgroup(int idx, unsigned long nr_pages,
284 				    struct hugetlb_cgroup *h_cg)
285 {
286 	if (hugetlb_cgroup_disabled() || !h_cg)
287 		return;
288 
289 	if (huge_page_order(&hstates[idx]) < HUGETLB_CGROUP_MIN_ORDER)
290 		return;
291 
292 	page_counter_uncharge(&h_cg->hugepage[idx], nr_pages);
293 	return;
294 }
295 
296 enum {
297 	RES_USAGE,
298 	RES_LIMIT,
299 	RES_MAX_USAGE,
300 	RES_FAILCNT,
301 };
302 
303 static u64 hugetlb_cgroup_read_u64(struct cgroup_subsys_state *css,
304 				   struct cftype *cft)
305 {
306 	struct page_counter *counter;
307 	struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_css(css);
308 
309 	counter = &h_cg->hugepage[MEMFILE_IDX(cft->private)];
310 
311 	switch (MEMFILE_ATTR(cft->private)) {
312 	case RES_USAGE:
313 		return (u64)page_counter_read(counter) * PAGE_SIZE;
314 	case RES_LIMIT:
315 		return (u64)counter->max * PAGE_SIZE;
316 	case RES_MAX_USAGE:
317 		return (u64)counter->watermark * PAGE_SIZE;
318 	case RES_FAILCNT:
319 		return counter->failcnt;
320 	default:
321 		BUG();
322 	}
323 }
324 
325 static int hugetlb_cgroup_read_u64_max(struct seq_file *seq, void *v)
326 {
327 	int idx;
328 	u64 val;
329 	struct cftype *cft = seq_cft(seq);
330 	unsigned long limit;
331 	struct page_counter *counter;
332 	struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_css(seq_css(seq));
333 
334 	idx = MEMFILE_IDX(cft->private);
335 	counter = &h_cg->hugepage[idx];
336 
337 	limit = round_down(PAGE_COUNTER_MAX,
338 			   1 << huge_page_order(&hstates[idx]));
339 
340 	switch (MEMFILE_ATTR(cft->private)) {
341 	case RES_USAGE:
342 		val = (u64)page_counter_read(counter);
343 		seq_printf(seq, "%llu\n", val * PAGE_SIZE);
344 		break;
345 	case RES_LIMIT:
346 		val = (u64)counter->max;
347 		if (val == limit)
348 			seq_puts(seq, "max\n");
349 		else
350 			seq_printf(seq, "%llu\n", val * PAGE_SIZE);
351 		break;
352 	default:
353 		BUG();
354 	}
355 
356 	return 0;
357 }
358 
359 static DEFINE_MUTEX(hugetlb_limit_mutex);
360 
361 static ssize_t hugetlb_cgroup_write(struct kernfs_open_file *of,
362 				    char *buf, size_t nbytes, loff_t off,
363 				    const char *max)
364 {
365 	int ret, idx;
366 	unsigned long nr_pages;
367 	struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_css(of_css(of));
368 
369 	if (hugetlb_cgroup_is_root(h_cg)) /* Can't set limit on root */
370 		return -EINVAL;
371 
372 	buf = strstrip(buf);
373 	ret = page_counter_memparse(buf, max, &nr_pages);
374 	if (ret)
375 		return ret;
376 
377 	idx = MEMFILE_IDX(of_cft(of)->private);
378 	nr_pages = round_down(nr_pages, 1 << huge_page_order(&hstates[idx]));
379 
380 	switch (MEMFILE_ATTR(of_cft(of)->private)) {
381 	case RES_LIMIT:
382 		mutex_lock(&hugetlb_limit_mutex);
383 		ret = page_counter_set_max(&h_cg->hugepage[idx], nr_pages);
384 		mutex_unlock(&hugetlb_limit_mutex);
385 		break;
386 	default:
387 		ret = -EINVAL;
388 		break;
389 	}
390 	return ret ?: nbytes;
391 }
392 
393 static ssize_t hugetlb_cgroup_write_legacy(struct kernfs_open_file *of,
394 					   char *buf, size_t nbytes, loff_t off)
395 {
396 	return hugetlb_cgroup_write(of, buf, nbytes, off, "-1");
397 }
398 
399 static ssize_t hugetlb_cgroup_write_dfl(struct kernfs_open_file *of,
400 					char *buf, size_t nbytes, loff_t off)
401 {
402 	return hugetlb_cgroup_write(of, buf, nbytes, off, "max");
403 }
404 
405 static ssize_t hugetlb_cgroup_reset(struct kernfs_open_file *of,
406 				    char *buf, size_t nbytes, loff_t off)
407 {
408 	int ret = 0;
409 	struct page_counter *counter;
410 	struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_css(of_css(of));
411 
412 	counter = &h_cg->hugepage[MEMFILE_IDX(of_cft(of)->private)];
413 
414 	switch (MEMFILE_ATTR(of_cft(of)->private)) {
415 	case RES_MAX_USAGE:
416 		page_counter_reset_watermark(counter);
417 		break;
418 	case RES_FAILCNT:
419 		counter->failcnt = 0;
420 		break;
421 	default:
422 		ret = -EINVAL;
423 		break;
424 	}
425 	return ret ?: nbytes;
426 }
427 
428 static char *mem_fmt(char *buf, int size, unsigned long hsize)
429 {
430 	if (hsize >= (1UL << 30))
431 		snprintf(buf, size, "%luGB", hsize >> 30);
432 	else if (hsize >= (1UL << 20))
433 		snprintf(buf, size, "%luMB", hsize >> 20);
434 	else
435 		snprintf(buf, size, "%luKB", hsize >> 10);
436 	return buf;
437 }
438 
439 static int __hugetlb_events_show(struct seq_file *seq, bool local)
440 {
441 	int idx;
442 	long max;
443 	struct cftype *cft = seq_cft(seq);
444 	struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_css(seq_css(seq));
445 
446 	idx = MEMFILE_IDX(cft->private);
447 
448 	if (local)
449 		max = atomic_long_read(&h_cg->events_local[idx][HUGETLB_MAX]);
450 	else
451 		max = atomic_long_read(&h_cg->events[idx][HUGETLB_MAX]);
452 
453 	seq_printf(seq, "max %lu\n", max);
454 
455 	return 0;
456 }
457 
458 static int hugetlb_events_show(struct seq_file *seq, void *v)
459 {
460 	return __hugetlb_events_show(seq, false);
461 }
462 
463 static int hugetlb_events_local_show(struct seq_file *seq, void *v)
464 {
465 	return __hugetlb_events_show(seq, true);
466 }
467 
468 static void __init __hugetlb_cgroup_file_dfl_init(int idx)
469 {
470 	char buf[32];
471 	struct cftype *cft;
472 	struct hstate *h = &hstates[idx];
473 
474 	/* format the size */
475 	mem_fmt(buf, 32, huge_page_size(h));
476 
477 	/* Add the limit file */
478 	cft = &h->cgroup_files_dfl[0];
479 	snprintf(cft->name, MAX_CFTYPE_NAME, "%s.max", buf);
480 	cft->private = MEMFILE_PRIVATE(idx, RES_LIMIT);
481 	cft->seq_show = hugetlb_cgroup_read_u64_max;
482 	cft->write = hugetlb_cgroup_write_dfl;
483 	cft->flags = CFTYPE_NOT_ON_ROOT;
484 
485 	/* Add the current usage file */
486 	cft = &h->cgroup_files_dfl[1];
487 	snprintf(cft->name, MAX_CFTYPE_NAME, "%s.current", buf);
488 	cft->private = MEMFILE_PRIVATE(idx, RES_USAGE);
489 	cft->seq_show = hugetlb_cgroup_read_u64_max;
490 	cft->flags = CFTYPE_NOT_ON_ROOT;
491 
492 	/* Add the events file */
493 	cft = &h->cgroup_files_dfl[2];
494 	snprintf(cft->name, MAX_CFTYPE_NAME, "%s.events", buf);
495 	cft->private = MEMFILE_PRIVATE(idx, 0);
496 	cft->seq_show = hugetlb_events_show;
497 	cft->file_offset = offsetof(struct hugetlb_cgroup, events_file[idx]),
498 	cft->flags = CFTYPE_NOT_ON_ROOT;
499 
500 	/* Add the events.local file */
501 	cft = &h->cgroup_files_dfl[3];
502 	snprintf(cft->name, MAX_CFTYPE_NAME, "%s.events.local", buf);
503 	cft->private = MEMFILE_PRIVATE(idx, 0);
504 	cft->seq_show = hugetlb_events_local_show;
505 	cft->file_offset = offsetof(struct hugetlb_cgroup,
506 				    events_local_file[idx]),
507 	cft->flags = CFTYPE_NOT_ON_ROOT;
508 
509 	/* NULL terminate the last cft */
510 	cft = &h->cgroup_files_dfl[4];
511 	memset(cft, 0, sizeof(*cft));
512 
513 	WARN_ON(cgroup_add_dfl_cftypes(&hugetlb_cgrp_subsys,
514 				       h->cgroup_files_dfl));
515 }
516 
517 static void __init __hugetlb_cgroup_file_legacy_init(int idx)
518 {
519 	char buf[32];
520 	struct cftype *cft;
521 	struct hstate *h = &hstates[idx];
522 
523 	/* format the size */
524 	mem_fmt(buf, 32, huge_page_size(h));
525 
526 	/* Add the limit file */
527 	cft = &h->cgroup_files_legacy[0];
528 	snprintf(cft->name, MAX_CFTYPE_NAME, "%s.limit_in_bytes", buf);
529 	cft->private = MEMFILE_PRIVATE(idx, RES_LIMIT);
530 	cft->read_u64 = hugetlb_cgroup_read_u64;
531 	cft->write = hugetlb_cgroup_write_legacy;
532 
533 	/* Add the usage file */
534 	cft = &h->cgroup_files_legacy[1];
535 	snprintf(cft->name, MAX_CFTYPE_NAME, "%s.usage_in_bytes", buf);
536 	cft->private = MEMFILE_PRIVATE(idx, RES_USAGE);
537 	cft->read_u64 = hugetlb_cgroup_read_u64;
538 
539 	/* Add the MAX usage file */
540 	cft = &h->cgroup_files_legacy[2];
541 	snprintf(cft->name, MAX_CFTYPE_NAME, "%s.max_usage_in_bytes", buf);
542 	cft->private = MEMFILE_PRIVATE(idx, RES_MAX_USAGE);
543 	cft->write = hugetlb_cgroup_reset;
544 	cft->read_u64 = hugetlb_cgroup_read_u64;
545 
546 	/* Add the failcntfile */
547 	cft = &h->cgroup_files_legacy[3];
548 	snprintf(cft->name, MAX_CFTYPE_NAME, "%s.failcnt", buf);
549 	cft->private  = MEMFILE_PRIVATE(idx, RES_FAILCNT);
550 	cft->write = hugetlb_cgroup_reset;
551 	cft->read_u64 = hugetlb_cgroup_read_u64;
552 
553 	/* NULL terminate the last cft */
554 	cft = &h->cgroup_files_legacy[4];
555 	memset(cft, 0, sizeof(*cft));
556 
557 	WARN_ON(cgroup_add_legacy_cftypes(&hugetlb_cgrp_subsys,
558 					  h->cgroup_files_legacy));
559 }
560 
561 static void __init __hugetlb_cgroup_file_init(int idx)
562 {
563 	__hugetlb_cgroup_file_dfl_init(idx);
564 	__hugetlb_cgroup_file_legacy_init(idx);
565 }
566 
567 void __init hugetlb_cgroup_file_init(void)
568 {
569 	struct hstate *h;
570 
571 	for_each_hstate(h) {
572 		/*
573 		 * Add cgroup control files only if the huge page consists
574 		 * of more than two normal pages. This is because we use
575 		 * page[2].private for storing cgroup details.
576 		 */
577 		if (huge_page_order(h) >= HUGETLB_CGROUP_MIN_ORDER)
578 			__hugetlb_cgroup_file_init(hstate_index(h));
579 	}
580 }
581 
582 /*
583  * hugetlb_lock will make sure a parallel cgroup rmdir won't happen
584  * when we migrate hugepages
585  */
586 void hugetlb_cgroup_migrate(struct page *oldhpage, struct page *newhpage)
587 {
588 	struct hugetlb_cgroup *h_cg;
589 	struct hstate *h = page_hstate(oldhpage);
590 
591 	if (hugetlb_cgroup_disabled())
592 		return;
593 
594 	VM_BUG_ON_PAGE(!PageHuge(oldhpage), oldhpage);
595 	spin_lock(&hugetlb_lock);
596 	h_cg = hugetlb_cgroup_from_page(oldhpage);
597 	set_hugetlb_cgroup(oldhpage, NULL);
598 
599 	/* move the h_cg details to new cgroup */
600 	set_hugetlb_cgroup(newhpage, h_cg);
601 	list_move(&newhpage->lru, &h->hugepage_activelist);
602 	spin_unlock(&hugetlb_lock);
603 	return;
604 }
605 
606 static struct cftype hugetlb_files[] = {
607 	{} /* terminate */
608 };
609 
610 struct cgroup_subsys hugetlb_cgrp_subsys = {
611 	.css_alloc	= hugetlb_cgroup_css_alloc,
612 	.css_offline	= hugetlb_cgroup_css_offline,
613 	.css_free	= hugetlb_cgroup_css_free,
614 	.dfl_cftypes	= hugetlb_files,
615 	.legacy_cftypes	= hugetlb_files,
616 };
617