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Linux/mm/hugetlb_cgroup.c

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  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 struct cgroup_subsys_state *
 71 hugetlb_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
 72 {
 73         struct hugetlb_cgroup *parent_h_cgroup = hugetlb_cgroup_from_css(parent_css);
 74         struct hugetlb_cgroup *h_cgroup;
 75         int idx;
 76 
 77         h_cgroup = kzalloc(sizeof(*h_cgroup), GFP_KERNEL);
 78         if (!h_cgroup)
 79                 return ERR_PTR(-ENOMEM);
 80 
 81         if (parent_h_cgroup) {
 82                 for (idx = 0; idx < HUGE_MAX_HSTATE; idx++)
 83                         page_counter_init(&h_cgroup->hugepage[idx],
 84                                           &parent_h_cgroup->hugepage[idx]);
 85         } else {
 86                 root_h_cgroup = h_cgroup;
 87                 for (idx = 0; idx < HUGE_MAX_HSTATE; idx++)
 88                         page_counter_init(&h_cgroup->hugepage[idx], NULL);
 89         }
 90         return &h_cgroup->css;
 91 }
 92 
 93 static void hugetlb_cgroup_css_free(struct cgroup_subsys_state *css)
 94 {
 95         struct hugetlb_cgroup *h_cgroup;
 96 
 97         h_cgroup = hugetlb_cgroup_from_css(css);
 98         kfree(h_cgroup);
 99 }
100 
101 
102 /*
103  * Should be called with hugetlb_lock held.
104  * Since we are holding hugetlb_lock, pages cannot get moved from
105  * active list or uncharged from the cgroup, So no need to get
106  * page reference and test for page active here. This function
107  * cannot fail.
108  */
109 static void hugetlb_cgroup_move_parent(int idx, struct hugetlb_cgroup *h_cg,
110                                        struct page *page)
111 {
112         unsigned int nr_pages;
113         struct page_counter *counter;
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         nr_pages = 1 << compound_order(page);
127         if (!parent) {
128                 parent = root_h_cgroup;
129                 /* root has no limit */
130                 page_counter_charge(&parent->hugepage[idx], nr_pages);
131         }
132         counter = &h_cg->hugepage[idx];
133         /* Take the pages off the local counter */
134         page_counter_cancel(counter, nr_pages);
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 page_counter *counter;
170         struct hugetlb_cgroup *h_cg = NULL;
171 
172         if (hugetlb_cgroup_disabled())
173                 goto done;
174         /*
175          * We don't charge any cgroup if the compound page have less
176          * than 3 pages.
177          */
178         if (huge_page_order(&hstates[idx]) < HUGETLB_CGROUP_MIN_ORDER)
179                 goto done;
180 again:
181         rcu_read_lock();
182         h_cg = hugetlb_cgroup_from_task(current);
183         if (!css_tryget_online(&h_cg->css)) {
184                 rcu_read_unlock();
185                 goto again;
186         }
187         rcu_read_unlock();
188 
189         ret = page_counter_try_charge(&h_cg->hugepage[idx], nr_pages, &counter);
190         css_put(&h_cg->css);
191 done:
192         *ptr = h_cg;
193         return ret;
194 }
195 
196 /* Should be called with hugetlb_lock held */
197 void hugetlb_cgroup_commit_charge(int idx, unsigned long nr_pages,
198                                   struct hugetlb_cgroup *h_cg,
199                                   struct page *page)
200 {
201         if (hugetlb_cgroup_disabled() || !h_cg)
202                 return;
203 
204         set_hugetlb_cgroup(page, h_cg);
205         return;
206 }
207 
208 /*
209  * Should be called with hugetlb_lock held
210  */
211 void hugetlb_cgroup_uncharge_page(int idx, unsigned long nr_pages,
212                                   struct page *page)
213 {
214         struct hugetlb_cgroup *h_cg;
215 
216         if (hugetlb_cgroup_disabled())
217                 return;
218         lockdep_assert_held(&hugetlb_lock);
219         h_cg = hugetlb_cgroup_from_page(page);
220         if (unlikely(!h_cg))
221                 return;
222         set_hugetlb_cgroup(page, NULL);
223         page_counter_uncharge(&h_cg->hugepage[idx], nr_pages);
224         return;
225 }
226 
227 void hugetlb_cgroup_uncharge_cgroup(int idx, unsigned long nr_pages,
228                                     struct hugetlb_cgroup *h_cg)
229 {
230         if (hugetlb_cgroup_disabled() || !h_cg)
231                 return;
232 
233         if (huge_page_order(&hstates[idx]) < HUGETLB_CGROUP_MIN_ORDER)
234                 return;
235 
236         page_counter_uncharge(&h_cg->hugepage[idx], nr_pages);
237         return;
238 }
239 
240 enum {
241         RES_USAGE,
242         RES_LIMIT,
243         RES_MAX_USAGE,
244         RES_FAILCNT,
245 };
246 
247 static u64 hugetlb_cgroup_read_u64(struct cgroup_subsys_state *css,
248                                    struct cftype *cft)
249 {
250         struct page_counter *counter;
251         struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_css(css);
252 
253         counter = &h_cg->hugepage[MEMFILE_IDX(cft->private)];
254 
255         switch (MEMFILE_ATTR(cft->private)) {
256         case RES_USAGE:
257                 return (u64)page_counter_read(counter) * PAGE_SIZE;
258         case RES_LIMIT:
259                 return (u64)counter->limit * PAGE_SIZE;
260         case RES_MAX_USAGE:
261                 return (u64)counter->watermark * PAGE_SIZE;
262         case RES_FAILCNT:
263                 return counter->failcnt;
264         default:
265                 BUG();
266         }
267 }
268 
269 static DEFINE_MUTEX(hugetlb_limit_mutex);
270 
271 static ssize_t hugetlb_cgroup_write(struct kernfs_open_file *of,
272                                     char *buf, size_t nbytes, loff_t off)
273 {
274         int ret, idx;
275         unsigned long nr_pages;
276         struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_css(of_css(of));
277 
278         if (hugetlb_cgroup_is_root(h_cg)) /* Can't set limit on root */
279                 return -EINVAL;
280 
281         buf = strstrip(buf);
282         ret = page_counter_memparse(buf, "-1", &nr_pages);
283         if (ret)
284                 return ret;
285 
286         idx = MEMFILE_IDX(of_cft(of)->private);
287 
288         switch (MEMFILE_ATTR(of_cft(of)->private)) {
289         case RES_LIMIT:
290                 mutex_lock(&hugetlb_limit_mutex);
291                 ret = page_counter_limit(&h_cg->hugepage[idx], nr_pages);
292                 mutex_unlock(&hugetlb_limit_mutex);
293                 break;
294         default:
295                 ret = -EINVAL;
296                 break;
297         }
298         return ret ?: nbytes;
299 }
300 
301 static ssize_t hugetlb_cgroup_reset(struct kernfs_open_file *of,
302                                     char *buf, size_t nbytes, loff_t off)
303 {
304         int ret = 0;
305         struct page_counter *counter;
306         struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_css(of_css(of));
307 
308         counter = &h_cg->hugepage[MEMFILE_IDX(of_cft(of)->private)];
309 
310         switch (MEMFILE_ATTR(of_cft(of)->private)) {
311         case RES_MAX_USAGE:
312                 page_counter_reset_watermark(counter);
313                 break;
314         case RES_FAILCNT:
315                 counter->failcnt = 0;
316                 break;
317         default:
318                 ret = -EINVAL;
319                 break;
320         }
321         return ret ?: nbytes;
322 }
323 
324 static char *mem_fmt(char *buf, int size, unsigned long hsize)
325 {
326         if (hsize >= (1UL << 30))
327                 snprintf(buf, size, "%luGB", hsize >> 30);
328         else if (hsize >= (1UL << 20))
329                 snprintf(buf, size, "%luMB", hsize >> 20);
330         else
331                 snprintf(buf, size, "%luKB", hsize >> 10);
332         return buf;
333 }
334 
335 static void __init __hugetlb_cgroup_file_init(int idx)
336 {
337         char buf[32];
338         struct cftype *cft;
339         struct hstate *h = &hstates[idx];
340 
341         /* format the size */
342         mem_fmt(buf, 32, huge_page_size(h));
343 
344         /* Add the limit file */
345         cft = &h->cgroup_files[0];
346         snprintf(cft->name, MAX_CFTYPE_NAME, "%s.limit_in_bytes", buf);
347         cft->private = MEMFILE_PRIVATE(idx, RES_LIMIT);
348         cft->read_u64 = hugetlb_cgroup_read_u64;
349         cft->write = hugetlb_cgroup_write;
350 
351         /* Add the usage file */
352         cft = &h->cgroup_files[1];
353         snprintf(cft->name, MAX_CFTYPE_NAME, "%s.usage_in_bytes", buf);
354         cft->private = MEMFILE_PRIVATE(idx, RES_USAGE);
355         cft->read_u64 = hugetlb_cgroup_read_u64;
356 
357         /* Add the MAX usage file */
358         cft = &h->cgroup_files[2];
359         snprintf(cft->name, MAX_CFTYPE_NAME, "%s.max_usage_in_bytes", buf);
360         cft->private = MEMFILE_PRIVATE(idx, RES_MAX_USAGE);
361         cft->write = hugetlb_cgroup_reset;
362         cft->read_u64 = hugetlb_cgroup_read_u64;
363 
364         /* Add the failcntfile */
365         cft = &h->cgroup_files[3];
366         snprintf(cft->name, MAX_CFTYPE_NAME, "%s.failcnt", buf);
367         cft->private  = MEMFILE_PRIVATE(idx, RES_FAILCNT);
368         cft->write = hugetlb_cgroup_reset;
369         cft->read_u64 = hugetlb_cgroup_read_u64;
370 
371         /* NULL terminate the last cft */
372         cft = &h->cgroup_files[4];
373         memset(cft, 0, sizeof(*cft));
374 
375         WARN_ON(cgroup_add_legacy_cftypes(&hugetlb_cgrp_subsys,
376                                           h->cgroup_files));
377 }
378 
379 void __init hugetlb_cgroup_file_init(void)
380 {
381         struct hstate *h;
382 
383         for_each_hstate(h) {
384                 /*
385                  * Add cgroup control files only if the huge page consists
386                  * of more than two normal pages. This is because we use
387                  * page[2].lru.next for storing cgroup details.
388                  */
389                 if (huge_page_order(h) >= HUGETLB_CGROUP_MIN_ORDER)
390                         __hugetlb_cgroup_file_init(hstate_index(h));
391         }
392 }
393 
394 /*
395  * hugetlb_lock will make sure a parallel cgroup rmdir won't happen
396  * when we migrate hugepages
397  */
398 void hugetlb_cgroup_migrate(struct page *oldhpage, struct page *newhpage)
399 {
400         struct hugetlb_cgroup *h_cg;
401         struct hstate *h = page_hstate(oldhpage);
402 
403         if (hugetlb_cgroup_disabled())
404                 return;
405 
406         VM_BUG_ON_PAGE(!PageHuge(oldhpage), oldhpage);
407         spin_lock(&hugetlb_lock);
408         h_cg = hugetlb_cgroup_from_page(oldhpage);
409         set_hugetlb_cgroup(oldhpage, NULL);
410 
411         /* move the h_cg details to new cgroup */
412         set_hugetlb_cgroup(newhpage, h_cg);
413         list_move(&newhpage->lru, &h->hugepage_activelist);
414         spin_unlock(&hugetlb_lock);
415         return;
416 }
417 
418 struct cgroup_subsys hugetlb_cgrp_subsys = {
419         .css_alloc      = hugetlb_cgroup_css_alloc,
420         .css_offline    = hugetlb_cgroup_css_offline,
421         .css_free       = hugetlb_cgroup_css_free,
422 };
423 

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