xref: /openbmc/linux/mm/hugetlb_cgroup.c (revision c2732114) 
1 /*
2  *
3  * Copyright IBM Corporation, 2012
4  * Author Aneesh Kumar K.V <aneesh.kumar@linux.vnet.ibm.com>
5  *
6  * This program is free software; you can redistribute it and/or modify it
7  * under the terms of version 2.1 of the GNU Lesser General Public License
8  * as published by the Free Software Foundation.
9  *
10  * This program is distributed in the hope that it would be useful, but
11  * WITHOUT ANY WARRANTY; without even the implied warranty of
12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
13  *
14  */
15 
16 #include <linux/cgroup.h>
17 #include <linux/slab.h>
18 #include <linux/hugetlb.h>
19 #include <linux/hugetlb_cgroup.h>
20 
21 struct hugetlb_cgroup {
22 	struct cgroup_subsys_state css;
23 	/*
24 	 * the counter to account for hugepages from hugetlb.
25 	 */
26 	struct res_counter hugepage[HUGE_MAX_HSTATE];
27 };
28 
29 #define MEMFILE_PRIVATE(x, val)	(((x) << 16) | (val))
30 #define MEMFILE_IDX(val)	(((val) >> 16) & 0xffff)
31 #define MEMFILE_ATTR(val)	((val) & 0xffff)
32 
33 static struct hugetlb_cgroup *root_h_cgroup __read_mostly;
34 
35 static inline
36 struct hugetlb_cgroup *hugetlb_cgroup_from_css(struct cgroup_subsys_state *s)
37 {
38 	return s ? container_of(s, struct hugetlb_cgroup, css) : NULL;
39 }
40 
41 static inline
42 struct hugetlb_cgroup *hugetlb_cgroup_from_task(struct task_struct *task)
43 {
44 	return hugetlb_cgroup_from_css(task_css(task, hugetlb_cgrp_id));
45 }
46 
47 static inline bool hugetlb_cgroup_is_root(struct hugetlb_cgroup *h_cg)
48 {
49 	return (h_cg == root_h_cgroup);
50 }
51 
52 static inline struct hugetlb_cgroup *
53 parent_hugetlb_cgroup(struct hugetlb_cgroup *h_cg)
54 {
55 	return hugetlb_cgroup_from_css(h_cg->css.parent);
56 }
57 
58 static inline bool hugetlb_cgroup_have_usage(struct hugetlb_cgroup *h_cg)
59 {
60 	int idx;
61 
62 	for (idx = 0; idx < hugetlb_max_hstate; idx++) {
63 		if ((res_counter_read_u64(&h_cg->hugepage[idx], RES_USAGE)) > 0)
64 			return true;
65 	}
66 	return false;
67 }
68 
69 static struct cgroup_subsys_state *
70 hugetlb_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
71 {
72 	struct hugetlb_cgroup *parent_h_cgroup = hugetlb_cgroup_from_css(parent_css);
73 	struct hugetlb_cgroup *h_cgroup;
74 	int idx;
75 
76 	h_cgroup = kzalloc(sizeof(*h_cgroup), GFP_KERNEL);
77 	if (!h_cgroup)
78 		return ERR_PTR(-ENOMEM);
79 
80 	if (parent_h_cgroup) {
81 		for (idx = 0; idx < HUGE_MAX_HSTATE; idx++)
82 			res_counter_init(&h_cgroup->hugepage[idx],
83 					 &parent_h_cgroup->hugepage[idx]);
84 	} else {
85 		root_h_cgroup = h_cgroup;
86 		for (idx = 0; idx < HUGE_MAX_HSTATE; idx++)
87 			res_counter_init(&h_cgroup->hugepage[idx], NULL);
88 	}
89 	return &h_cgroup->css;
90 }
91 
92 static void hugetlb_cgroup_css_free(struct cgroup_subsys_state *css)
93 {
94 	struct hugetlb_cgroup *h_cgroup;
95 
96 	h_cgroup = hugetlb_cgroup_from_css(css);
97 	kfree(h_cgroup);
98 }
99 
100 
101 /*
102  * Should be called with hugetlb_lock held.
103  * Since we are holding hugetlb_lock, pages cannot get moved from
104  * active list or uncharged from the cgroup, So no need to get
105  * page reference and test for page active here. This function
106  * cannot fail.
107  */
108 static void hugetlb_cgroup_move_parent(int idx, struct hugetlb_cgroup *h_cg,
109 				       struct page *page)
110 {
111 	int csize;
112 	struct res_counter *counter;
113 	struct res_counter *fail_res;
114 	struct hugetlb_cgroup *page_hcg;
115 	struct hugetlb_cgroup *parent = parent_hugetlb_cgroup(h_cg);
116 
117 	page_hcg = hugetlb_cgroup_from_page(page);
118 	/*
119 	 * We can have pages in active list without any cgroup
120 	 * ie, hugepage with less than 3 pages. We can safely
121 	 * ignore those pages.
122 	 */
123 	if (!page_hcg || page_hcg != h_cg)
124 		goto out;
125 
126 	csize = PAGE_SIZE << compound_order(page);
127 	if (!parent) {
128 		parent = root_h_cgroup;
129 		/* root has no limit */
130 		res_counter_charge_nofail(&parent->hugepage[idx],
131 					  csize, &fail_res);
132 	}
133 	counter = &h_cg->hugepage[idx];
134 	res_counter_uncharge_until(counter, counter->parent, csize);
135 
136 	set_hugetlb_cgroup(page, parent);
137 out:
138 	return;
139 }
140 
141 /*
142  * Force the hugetlb cgroup to empty the hugetlb resources by moving them to
143  * the parent cgroup.
144  */
145 static void hugetlb_cgroup_css_offline(struct cgroup_subsys_state *css)
146 {
147 	struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_css(css);
148 	struct hstate *h;
149 	struct page *page;
150 	int idx = 0;
151 
152 	do {
153 		for_each_hstate(h) {
154 			spin_lock(&hugetlb_lock);
155 			list_for_each_entry(page, &h->hugepage_activelist, lru)
156 				hugetlb_cgroup_move_parent(idx, h_cg, page);
157 
158 			spin_unlock(&hugetlb_lock);
159 			idx++;
160 		}
161 		cond_resched();
162 	} while (hugetlb_cgroup_have_usage(h_cg));
163 }
164 
165 int hugetlb_cgroup_charge_cgroup(int idx, unsigned long nr_pages,
166 				 struct hugetlb_cgroup **ptr)
167 {
168 	int ret = 0;
169 	struct res_counter *fail_res;
170 	struct hugetlb_cgroup *h_cg = NULL;
171 	unsigned long csize = nr_pages * PAGE_SIZE;
172 
173 	if (hugetlb_cgroup_disabled())
174 		goto done;
175 	/*
176 	 * We don't charge any cgroup if the compound page have less
177 	 * than 3 pages.
178 	 */
179 	if (huge_page_order(&hstates[idx]) < HUGETLB_CGROUP_MIN_ORDER)
180 		goto done;
181 again:
182 	rcu_read_lock();
183 	h_cg = hugetlb_cgroup_from_task(current);
184 	if (!css_tryget_online(&h_cg->css)) {
185 		rcu_read_unlock();
186 		goto again;
187 	}
188 	rcu_read_unlock();
189 
190 	ret = res_counter_charge(&h_cg->hugepage[idx], csize, &fail_res);
191 	css_put(&h_cg->css);
192 done:
193 	*ptr = h_cg;
194 	return ret;
195 }
196 
197 /* Should be called with hugetlb_lock held */
198 void hugetlb_cgroup_commit_charge(int idx, unsigned long nr_pages,
199 				  struct hugetlb_cgroup *h_cg,
200 				  struct page *page)
201 {
202 	if (hugetlb_cgroup_disabled() || !h_cg)
203 		return;
204 
205 	set_hugetlb_cgroup(page, h_cg);
206 	return;
207 }
208 
209 /*
210  * Should be called with hugetlb_lock held
211  */
212 void hugetlb_cgroup_uncharge_page(int idx, unsigned long nr_pages,
213 				  struct page *page)
214 {
215 	struct hugetlb_cgroup *h_cg;
216 	unsigned long csize = nr_pages * PAGE_SIZE;
217 
218 	if (hugetlb_cgroup_disabled())
219 		return;
220 	lockdep_assert_held(&hugetlb_lock);
221 	h_cg = hugetlb_cgroup_from_page(page);
222 	if (unlikely(!h_cg))
223 		return;
224 	set_hugetlb_cgroup(page, NULL);
225 	res_counter_uncharge(&h_cg->hugepage[idx], csize);
226 	return;
227 }
228 
229 void hugetlb_cgroup_uncharge_cgroup(int idx, unsigned long nr_pages,
230 				    struct hugetlb_cgroup *h_cg)
231 {
232 	unsigned long csize = nr_pages * PAGE_SIZE;
233 
234 	if (hugetlb_cgroup_disabled() || !h_cg)
235 		return;
236 
237 	if (huge_page_order(&hstates[idx]) < HUGETLB_CGROUP_MIN_ORDER)
238 		return;
239 
240 	res_counter_uncharge(&h_cg->hugepage[idx], csize);
241 	return;
242 }
243 
244 static u64 hugetlb_cgroup_read_u64(struct cgroup_subsys_state *css,
245 				   struct cftype *cft)
246 {
247 	int idx, name;
248 	struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_css(css);
249 
250 	idx = MEMFILE_IDX(cft->private);
251 	name = MEMFILE_ATTR(cft->private);
252 
253 	return res_counter_read_u64(&h_cg->hugepage[idx], name);
254 }
255 
256 static ssize_t hugetlb_cgroup_write(struct kernfs_open_file *of,
257 				    char *buf, size_t nbytes, loff_t off)
258 {
259 	int idx, name, ret;
260 	unsigned long long val;
261 	struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_css(of_css(of));
262 
263 	buf = strstrip(buf);
264 	idx = MEMFILE_IDX(of_cft(of)->private);
265 	name = MEMFILE_ATTR(of_cft(of)->private);
266 
267 	switch (name) {
268 	case RES_LIMIT:
269 		if (hugetlb_cgroup_is_root(h_cg)) {
270 			/* Can't set limit on root */
271 			ret = -EINVAL;
272 			break;
273 		}
274 		/* This function does all necessary parse...reuse it */
275 		ret = res_counter_memparse_write_strategy(buf, &val);
276 		if (ret)
277 			break;
278 		val = ALIGN(val, 1ULL << huge_page_shift(&hstates[idx]));
279 		ret = res_counter_set_limit(&h_cg->hugepage[idx], val);
280 		break;
281 	default:
282 		ret = -EINVAL;
283 		break;
284 	}
285 	return ret ?: nbytes;
286 }
287 
288 static ssize_t hugetlb_cgroup_reset(struct kernfs_open_file *of,
289 				    char *buf, size_t nbytes, loff_t off)
290 {
291 	int idx, name, ret = 0;
292 	struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_css(of_css(of));
293 
294 	idx = MEMFILE_IDX(of_cft(of)->private);
295 	name = MEMFILE_ATTR(of_cft(of)->private);
296 
297 	switch (name) {
298 	case RES_MAX_USAGE:
299 		res_counter_reset_max(&h_cg->hugepage[idx]);
300 		break;
301 	case RES_FAILCNT:
302 		res_counter_reset_failcnt(&h_cg->hugepage[idx]);
303 		break;
304 	default:
305 		ret = -EINVAL;
306 		break;
307 	}
308 	return ret ?: nbytes;
309 }
310 
311 static char *mem_fmt(char *buf, int size, unsigned long hsize)
312 {
313 	if (hsize >= (1UL << 30))
314 		snprintf(buf, size, "%luGB", hsize >> 30);
315 	else if (hsize >= (1UL << 20))
316 		snprintf(buf, size, "%luMB", hsize >> 20);
317 	else
318 		snprintf(buf, size, "%luKB", hsize >> 10);
319 	return buf;
320 }
321 
322 static void __init __hugetlb_cgroup_file_init(int idx)
323 {
324 	char buf[32];
325 	struct cftype *cft;
326 	struct hstate *h = &hstates[idx];
327 
328 	/* format the size */
329 	mem_fmt(buf, 32, huge_page_size(h));
330 
331 	/* Add the limit file */
332 	cft = &h->cgroup_files[0];
333 	snprintf(cft->name, MAX_CFTYPE_NAME, "%s.limit_in_bytes", buf);
334 	cft->private = MEMFILE_PRIVATE(idx, RES_LIMIT);
335 	cft->read_u64 = hugetlb_cgroup_read_u64;
336 	cft->write = hugetlb_cgroup_write;
337 
338 	/* Add the usage file */
339 	cft = &h->cgroup_files[1];
340 	snprintf(cft->name, MAX_CFTYPE_NAME, "%s.usage_in_bytes", buf);
341 	cft->private = MEMFILE_PRIVATE(idx, RES_USAGE);
342 	cft->read_u64 = hugetlb_cgroup_read_u64;
343 
344 	/* Add the MAX usage file */
345 	cft = &h->cgroup_files[2];
346 	snprintf(cft->name, MAX_CFTYPE_NAME, "%s.max_usage_in_bytes", buf);
347 	cft->private = MEMFILE_PRIVATE(idx, RES_MAX_USAGE);
348 	cft->write = hugetlb_cgroup_reset;
349 	cft->read_u64 = hugetlb_cgroup_read_u64;
350 
351 	/* Add the failcntfile */
352 	cft = &h->cgroup_files[3];
353 	snprintf(cft->name, MAX_CFTYPE_NAME, "%s.failcnt", buf);
354 	cft->private  = MEMFILE_PRIVATE(idx, RES_FAILCNT);
355 	cft->write = hugetlb_cgroup_reset;
356 	cft->read_u64 = hugetlb_cgroup_read_u64;
357 
358 	/* NULL terminate the last cft */
359 	cft = &h->cgroup_files[4];
360 	memset(cft, 0, sizeof(*cft));
361 
362 	WARN_ON(cgroup_add_legacy_cftypes(&hugetlb_cgrp_subsys,
363 					  h->cgroup_files));
364 }
365 
366 void __init hugetlb_cgroup_file_init(void)
367 {
368 	struct hstate *h;
369 
370 	for_each_hstate(h) {
371 		/*
372 		 * Add cgroup control files only if the huge page consists
373 		 * of more than two normal pages. This is because we use
374 		 * page[2].lru.next for storing cgroup details.
375 		 */
376 		if (huge_page_order(h) >= HUGETLB_CGROUP_MIN_ORDER)
377 			__hugetlb_cgroup_file_init(hstate_index(h));
378 	}
379 }
380 
381 /*
382  * hugetlb_lock will make sure a parallel cgroup rmdir won't happen
383  * when we migrate hugepages
384  */
385 void hugetlb_cgroup_migrate(struct page *oldhpage, struct page *newhpage)
386 {
387 	struct hugetlb_cgroup *h_cg;
388 	struct hstate *h = page_hstate(oldhpage);
389 
390 	if (hugetlb_cgroup_disabled())
391 		return;
392 
393 	VM_BUG_ON_PAGE(!PageHuge(oldhpage), oldhpage);
394 	spin_lock(&hugetlb_lock);
395 	h_cg = hugetlb_cgroup_from_page(oldhpage);
396 	set_hugetlb_cgroup(oldhpage, NULL);
397 
398 	/* move the h_cg details to new cgroup */
399 	set_hugetlb_cgroup(newhpage, h_cg);
400 	list_move(&newhpage->lru, &h->hugepage_activelist);
401 	spin_unlock(&hugetlb_lock);
402 	return;
403 }
404 
405 struct cgroup_subsys hugetlb_cgrp_subsys = {
406 	.css_alloc	= hugetlb_cgroup_css_alloc,
407 	.css_offline	= hugetlb_cgroup_css_offline,
408 	.css_free	= hugetlb_cgroup_css_free,
409 };
410