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Linux/mm/hugetlb_cgroup.c

  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/page_counter.h>
 18 #include <linux/slab.h>
 19 #include <linux/hugetlb.h>
 20 #include <linux/hugetlb_cgroup.h>
 21 
 22 struct hugetlb_cgroup {
 23         struct cgroup_subsys_state css;
 24         /*
 25          * the counter to account for hugepages from hugetlb.
 26          */
 27         struct page_counter hugepage[HUGE_MAX_HSTATE];
 28 };
 29 
 30 #define MEMFILE_PRIVATE(x, val) (((x) << 16) | (val))
 31 #define MEMFILE_IDX(val)        (((val) >> 16) & 0xffff)
 32 #define MEMFILE_ATTR(val)       ((val) & 0xffff)
 33 
 34 static struct hugetlb_cgroup *root_h_cgroup __read_mostly;
 35 
 36 static inline
 37 struct hugetlb_cgroup *hugetlb_cgroup_from_css(struct cgroup_subsys_state *s)
 38 {
 39         return s ? container_of(s, struct hugetlb_cgroup, css) : NULL;
 40 }
 41 
 42 static inline
 43 struct hugetlb_cgroup *hugetlb_cgroup_from_task(struct task_struct *task)
 44 {
 45         return hugetlb_cgroup_from_css(task_css(task, hugetlb_cgrp_id));
 46 }
 47 
 48 static inline bool hugetlb_cgroup_is_root(struct hugetlb_cgroup *h_cg)
 49 {
 50         return (h_cg == root_h_cgroup);
 51 }
 52 
 53 static inline struct hugetlb_cgroup *
 54 parent_hugetlb_cgroup(struct hugetlb_cgroup *h_cg)
 55 {
 56         return hugetlb_cgroup_from_css(h_cg->css.parent);
 57 }
 58 
 59 static inline bool hugetlb_cgroup_have_usage(struct hugetlb_cgroup *h_cg)
 60 {
 61         int idx;
 62 
 63         for (idx = 0; idx < hugetlb_max_hstate; idx++) {
 64                 if (page_counter_read(&h_cg->hugepage[idx]))
 65                         return true;
 66         }
 67         return false;
 68 }
 69 
 70 static void hugetlb_cgroup_init(struct hugetlb_cgroup *h_cgroup,
 71                                 struct hugetlb_cgroup *parent_h_cgroup)
 72 {
 73         int idx;
 74 
 75         for (idx = 0; idx < HUGE_MAX_HSTATE; idx++) {
 76                 struct page_counter *counter = &h_cgroup->hugepage[idx];
 77                 struct page_counter *parent = NULL;
 78                 unsigned long limit;
 79                 int ret;
 80 
 81                 if (parent_h_cgroup)
 82                         parent = &parent_h_cgroup->hugepage[idx];
 83                 page_counter_init(counter, parent);
 84 
 85                 limit = round_down(PAGE_COUNTER_MAX,
 86                                    1 << huge_page_order(&hstates[idx]));
 87                 ret = page_counter_limit(counter, limit);
 88                 VM_BUG_ON(ret);
 89         }
 90 }
 91 
 92 static struct cgroup_subsys_state *
 93 hugetlb_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
 94 {
 95         struct hugetlb_cgroup *parent_h_cgroup = hugetlb_cgroup_from_css(parent_css);
 96         struct hugetlb_cgroup *h_cgroup;
 97 
 98         h_cgroup = kzalloc(sizeof(*h_cgroup), GFP_KERNEL);
 99         if (!h_cgroup)
100                 return ERR_PTR(-ENOMEM);
101 
102         if (!parent_h_cgroup)
103                 root_h_cgroup = h_cgroup;
104 
105         hugetlb_cgroup_init(h_cgroup, parent_h_cgroup);
106         return &h_cgroup->css;
107 }
108 
109 static void hugetlb_cgroup_css_free(struct cgroup_subsys_state *css)
110 {
111         struct hugetlb_cgroup *h_cgroup;
112 
113         h_cgroup = hugetlb_cgroup_from_css(css);
114         kfree(h_cgroup);
115 }
116 
117 
118 /*
119  * Should be called with hugetlb_lock held.
120  * Since we are holding hugetlb_lock, pages cannot get moved from
121  * active list or uncharged from the cgroup, So no need to get
122  * page reference and test for page active here. This function
123  * cannot fail.
124  */
125 static void hugetlb_cgroup_move_parent(int idx, struct hugetlb_cgroup *h_cg,
126                                        struct page *page)
127 {
128         unsigned int nr_pages;
129         struct page_counter *counter;
130         struct hugetlb_cgroup *page_hcg;
131         struct hugetlb_cgroup *parent = parent_hugetlb_cgroup(h_cg);
132 
133         page_hcg = hugetlb_cgroup_from_page(page);
134         /*
135          * We can have pages in active list without any cgroup
136          * ie, hugepage with less than 3 pages. We can safely
137          * ignore those pages.
138          */
139         if (!page_hcg || page_hcg != h_cg)
140                 goto out;
141 
142         nr_pages = 1 << compound_order(page);
143         if (!parent) {
144                 parent = root_h_cgroup;
145                 /* root has no limit */
146                 page_counter_charge(&parent->hugepage[idx], nr_pages);
147         }
148         counter = &h_cg->hugepage[idx];
149         /* Take the pages off the local counter */
150         page_counter_cancel(counter, nr_pages);
151 
152         set_hugetlb_cgroup(page, parent);
153 out:
154         return;
155 }
156 
157 /*
158  * Force the hugetlb cgroup to empty the hugetlb resources by moving them to
159  * the parent cgroup.
160  */
161 static void hugetlb_cgroup_css_offline(struct cgroup_subsys_state *css)
162 {
163         struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_css(css);
164         struct hstate *h;
165         struct page *page;
166         int idx = 0;
167 
168         do {
169                 for_each_hstate(h) {
170                         spin_lock(&hugetlb_lock);
171                         list_for_each_entry(page, &h->hugepage_activelist, lru)
172                                 hugetlb_cgroup_move_parent(idx, h_cg, page);
173 
174                         spin_unlock(&hugetlb_lock);
175                         idx++;
176                 }
177                 cond_resched();
178         } while (hugetlb_cgroup_have_usage(h_cg));
179 }
180 
181 int hugetlb_cgroup_charge_cgroup(int idx, unsigned long nr_pages,
182                                  struct hugetlb_cgroup **ptr)
183 {
184         int ret = 0;
185         struct page_counter *counter;
186         struct hugetlb_cgroup *h_cg = NULL;
187 
188         if (hugetlb_cgroup_disabled())
189                 goto done;
190         /*
191          * We don't charge any cgroup if the compound page have less
192          * than 3 pages.
193          */
194         if (huge_page_order(&hstates[idx]) < HUGETLB_CGROUP_MIN_ORDER)
195                 goto done;
196 again:
197         rcu_read_lock();
198         h_cg = hugetlb_cgroup_from_task(current);
199         if (!css_tryget_online(&h_cg->css)) {
200                 rcu_read_unlock();
201                 goto again;
202         }
203         rcu_read_unlock();
204 
205         if (!page_counter_try_charge(&h_cg->hugepage[idx], nr_pages, &counter))
206                 ret = -ENOMEM;
207         css_put(&h_cg->css);
208 done:
209         *ptr = h_cg;
210         return ret;
211 }
212 
213 /* Should be called with hugetlb_lock held */
214 void hugetlb_cgroup_commit_charge(int idx, unsigned long nr_pages,
215                                   struct hugetlb_cgroup *h_cg,
216                                   struct page *page)
217 {
218         if (hugetlb_cgroup_disabled() || !h_cg)
219                 return;
220 
221         set_hugetlb_cgroup(page, h_cg);
222         return;
223 }
224 
225 /*
226  * Should be called with hugetlb_lock held
227  */
228 void hugetlb_cgroup_uncharge_page(int idx, unsigned long nr_pages,
229                                   struct page *page)
230 {
231         struct hugetlb_cgroup *h_cg;
232 
233         if (hugetlb_cgroup_disabled())
234                 return;
235         lockdep_assert_held(&hugetlb_lock);
236         h_cg = hugetlb_cgroup_from_page(page);
237         if (unlikely(!h_cg))
238                 return;
239         set_hugetlb_cgroup(page, NULL);
240         page_counter_uncharge(&h_cg->hugepage[idx], nr_pages);
241         return;
242 }
243 
244 void hugetlb_cgroup_uncharge_cgroup(int idx, unsigned long nr_pages,
245                                     struct hugetlb_cgroup *h_cg)
246 {
247         if (hugetlb_cgroup_disabled() || !h_cg)
248                 return;
249 
250         if (huge_page_order(&hstates[idx]) < HUGETLB_CGROUP_MIN_ORDER)
251                 return;
252 
253         page_counter_uncharge(&h_cg->hugepage[idx], nr_pages);
254         return;
255 }
256 
257 enum {
258         RES_USAGE,
259         RES_LIMIT,
260         RES_MAX_USAGE,
261         RES_FAILCNT,
262 };
263 
264 static u64 hugetlb_cgroup_read_u64(struct cgroup_subsys_state *css,
265                                    struct cftype *cft)
266 {
267         struct page_counter *counter;
268         struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_css(css);
269 
270         counter = &h_cg->hugepage[MEMFILE_IDX(cft->private)];
271 
272         switch (MEMFILE_ATTR(cft->private)) {
273         case RES_USAGE:
274                 return (u64)page_counter_read(counter) * PAGE_SIZE;
275         case RES_LIMIT:
276                 return (u64)counter->limit * PAGE_SIZE;
277         case RES_MAX_USAGE:
278                 return (u64)counter->watermark * PAGE_SIZE;
279         case RES_FAILCNT:
280                 return counter->failcnt;
281         default:
282                 BUG();
283         }
284 }
285 
286 static DEFINE_MUTEX(hugetlb_limit_mutex);
287 
288 static ssize_t hugetlb_cgroup_write(struct kernfs_open_file *of,
289                                     char *buf, size_t nbytes, loff_t off)
290 {
291         int ret, idx;
292         unsigned long nr_pages;
293         struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_css(of_css(of));
294 
295         if (hugetlb_cgroup_is_root(h_cg)) /* Can't set limit on root */
296                 return -EINVAL;
297 
298         buf = strstrip(buf);
299         ret = page_counter_memparse(buf, "-1", &nr_pages);
300         if (ret)
301                 return ret;
302 
303         idx = MEMFILE_IDX(of_cft(of)->private);
304         nr_pages = round_down(nr_pages, 1 << huge_page_order(&hstates[idx]));
305 
306         switch (MEMFILE_ATTR(of_cft(of)->private)) {
307         case RES_LIMIT:
308                 mutex_lock(&hugetlb_limit_mutex);
309                 ret = page_counter_limit(&h_cg->hugepage[idx], nr_pages);
310                 mutex_unlock(&hugetlb_limit_mutex);
311                 break;
312         default:
313                 ret = -EINVAL;
314                 break;
315         }
316         return ret ?: nbytes;
317 }
318 
319 static ssize_t hugetlb_cgroup_reset(struct kernfs_open_file *of,
320                                     char *buf, size_t nbytes, loff_t off)
321 {
322         int ret = 0;
323         struct page_counter *counter;
324         struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_css(of_css(of));
325 
326         counter = &h_cg->hugepage[MEMFILE_IDX(of_cft(of)->private)];
327 
328         switch (MEMFILE_ATTR(of_cft(of)->private)) {
329         case RES_MAX_USAGE:
330                 page_counter_reset_watermark(counter);
331                 break;
332         case RES_FAILCNT:
333                 counter->failcnt = 0;
334                 break;
335         default:
336                 ret = -EINVAL;
337                 break;
338         }
339         return ret ?: nbytes;
340 }
341 
342 static char *mem_fmt(char *buf, int size, unsigned long hsize)
343 {
344         if (hsize >= (1UL << 30))
345                 snprintf(buf, size, "%luGB", hsize >> 30);
346         else if (hsize >= (1UL << 20))
347                 snprintf(buf, size, "%luMB", hsize >> 20);
348         else
349                 snprintf(buf, size, "%luKB", hsize >> 10);
350         return buf;
351 }
352 
353 static void __init __hugetlb_cgroup_file_init(int idx)
354 {
355         char buf[32];
356         struct cftype *cft;
357         struct hstate *h = &hstates[idx];
358 
359         /* format the size */
360         mem_fmt(buf, 32, huge_page_size(h));
361 
362         /* Add the limit file */
363         cft = &h->cgroup_files[0];
364         snprintf(cft->name, MAX_CFTYPE_NAME, "%s.limit_in_bytes", buf);
365         cft->private = MEMFILE_PRIVATE(idx, RES_LIMIT);
366         cft->read_u64 = hugetlb_cgroup_read_u64;
367         cft->write = hugetlb_cgroup_write;
368 
369         /* Add the usage file */
370         cft = &h->cgroup_files[1];
371         snprintf(cft->name, MAX_CFTYPE_NAME, "%s.usage_in_bytes", buf);
372         cft->private = MEMFILE_PRIVATE(idx, RES_USAGE);
373         cft->read_u64 = hugetlb_cgroup_read_u64;
374 
375         /* Add the MAX usage file */
376         cft = &h->cgroup_files[2];
377         snprintf(cft->name, MAX_CFTYPE_NAME, "%s.max_usage_in_bytes", buf);
378         cft->private = MEMFILE_PRIVATE(idx, RES_MAX_USAGE);
379         cft->write = hugetlb_cgroup_reset;
380         cft->read_u64 = hugetlb_cgroup_read_u64;
381 
382         /* Add the failcntfile */
383         cft = &h->cgroup_files[3];
384         snprintf(cft->name, MAX_CFTYPE_NAME, "%s.failcnt", buf);
385         cft->private  = MEMFILE_PRIVATE(idx, RES_FAILCNT);
386         cft->write = hugetlb_cgroup_reset;
387         cft->read_u64 = hugetlb_cgroup_read_u64;
388 
389         /* NULL terminate the last cft */
390         cft = &h->cgroup_files[4];
391         memset(cft, 0, sizeof(*cft));
392 
393         WARN_ON(cgroup_add_legacy_cftypes(&hugetlb_cgrp_subsys,
394                                           h->cgroup_files));
395 }
396 
397 void __init hugetlb_cgroup_file_init(void)
398 {
399         struct hstate *h;
400 
401         for_each_hstate(h) {
402                 /*
403                  * Add cgroup control files only if the huge page consists
404                  * of more than two normal pages. This is because we use
405                  * page[2].private for storing cgroup details.
406                  */
407                 if (huge_page_order(h) >= HUGETLB_CGROUP_MIN_ORDER)
408                         __hugetlb_cgroup_file_init(hstate_index(h));
409         }
410 }
411 
412 /*
413  * hugetlb_lock will make sure a parallel cgroup rmdir won't happen
414  * when we migrate hugepages
415  */
416 void hugetlb_cgroup_migrate(struct page *oldhpage, struct page *newhpage)
417 {
418         struct hugetlb_cgroup *h_cg;
419         struct hstate *h = page_hstate(oldhpage);
420 
421         if (hugetlb_cgroup_disabled())
422                 return;
423 
424         VM_BUG_ON_PAGE(!PageHuge(oldhpage), oldhpage);
425         spin_lock(&hugetlb_lock);
426         h_cg = hugetlb_cgroup_from_page(oldhpage);
427         set_hugetlb_cgroup(oldhpage, NULL);
428 
429         /* move the h_cg details to new cgroup */
430         set_hugetlb_cgroup(newhpage, h_cg);
431         list_move(&newhpage->lru, &h->hugepage_activelist);
432         spin_unlock(&hugetlb_lock);
433         return;
434 }
435 
436 struct cgroup_subsys hugetlb_cgrp_subsys = {
437         .css_alloc      = hugetlb_cgroup_css_alloc,
438         .css_offline    = hugetlb_cgroup_css_offline,
439         .css_free       = hugetlb_cgroup_css_free,
440 };
441 

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