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 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, &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 };