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/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 struct cgroup_subsys hugetlb_subsys __read_mostly;
  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_subsys_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(css_parent(&h_cg->css));
  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 ((res_counter_read_u64(&h_cg->hugepage[idx], RES_USAGE)) > 0)
  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                         res_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                         res_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         int csize;
 113         struct res_counter *counter;
 114         struct res_counter *fail_res;
 115         struct hugetlb_cgroup *page_hcg;
 116         struct hugetlb_cgroup *parent = parent_hugetlb_cgroup(h_cg);
 117
 118         page_hcg = hugetlb_cgroup_from_page(page);
 119         /*
 120          * We can have pages in active list without any cgroup
 121          * ie, hugepage with less than 3 pages. We can safely
 122          * ignore those pages.
 123          */
 124         if (!page_hcg || page_hcg != h_cg)
 125                 goto out;
 126
 127         csize = PAGE_SIZE << compound_order(page);
 128         if (!parent) {
 129                 parent = root_h_cgroup;
 130                 /* root has no limit */
 131                 res_counter_charge_nofail(&parent->hugepage[idx],
 132                                           csize, &fail_res);
 133         }
 134         counter = &h_cg->hugepage[idx];
 135         res_counter_uncharge_until(counter, counter->parent, csize);
 136
 137         set_hugetlb_cgroup(page, parent);
 138 out:
 139         return;
 140 }
 141
 142 /*
 143  * Force the hugetlb cgroup to empty the hugetlb resources by moving them to
 144  * the parent cgroup.
 145  */
 146 static void hugetlb_cgroup_css_offline(struct cgroup_subsys_state *css)
 147 {
 148         struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_css(css);
 149         struct hstate *h;
 150         struct page *page;
 151         int idx = 0;
 152
 153         do {
 154                 for_each_hstate(h) {
 155                         spin_lock(&hugetlb_lock);
 156                         list_for_each_entry(page, &h->hugepage_activelist, lru)
 157                                 hugetlb_cgroup_move_parent(idx, h_cg, page);
 158
 159                         spin_unlock(&hugetlb_lock);
 160                         idx++;
 161                 }
 162                 cond_resched();
 163         } while (hugetlb_cgroup_have_usage(h_cg));
 164 }
 165
 166 int hugetlb_cgroup_charge_cgroup(int idx, unsigned long nr_pages,
 167                                  struct hugetlb_cgroup **ptr)
 168 {
 169         int ret = 0;
 170         struct res_counter *fail_res;
 171         struct hugetlb_cgroup *h_cg = NULL;
 172         unsigned long csize = nr_pages * PAGE_SIZE;
 173
 174         if (hugetlb_cgroup_disabled())
 175                 goto done;
 176         /*
 177          * We don't charge any cgroup if the compound page have less
 178          * than 3 pages.
 179          */
 180         if (huge_page_order(&hstates[idx]) < HUGETLB_CGROUP_MIN_ORDER)
 181                 goto done;
 182 again:
 183         rcu_read_lock();
 184         h_cg = hugetlb_cgroup_from_task(current);
 185         if (!css_tryget(&h_cg->css)) {
 186                 rcu_read_unlock();
 187                 goto again;
 188         }
 189         rcu_read_unlock();
 190
 191         ret = res_counter_charge(&h_cg->hugepage[idx], csize, &fail_res);
 192         css_put(&h_cg->css);
 193 done:
 194         *ptr = h_cg;
 195         return ret;
 196 }
 197
 198 /* Should be called with hugetlb_lock held */
 199 void hugetlb_cgroup_commit_charge(int idx, unsigned long nr_pages,
 200                                   struct hugetlb_cgroup *h_cg,
 201                                   struct page *page)
 202 {
 203         if (hugetlb_cgroup_disabled() || !h_cg)
 204                 return;
 205
 206         set_hugetlb_cgroup(page, h_cg);
 207         return;
 208 }
 209
 210 /*
 211  * Should be called with hugetlb_lock held
 212  */
 213 void hugetlb_cgroup_uncharge_page(int idx, unsigned long nr_pages,
 214                                   struct page *page)
 215 {
 216         struct hugetlb_cgroup *h_cg;
 217         unsigned long csize = nr_pages * PAGE_SIZE;
 218
 219         if (hugetlb_cgroup_disabled())
 220                 return;
 221         VM_BUG_ON(!spin_is_locked(&hugetlb_lock));
 222         h_cg = hugetlb_cgroup_from_page(page);
 223         if (unlikely(!h_cg))
 224                 return;
 225         set_hugetlb_cgroup(page, NULL);
 226         res_counter_uncharge(&h_cg->hugepage[idx], csize);
 227         return;
 228 }
 229
 230 void hugetlb_cgroup_uncharge_cgroup(int idx, unsigned long nr_pages,
 231                                     struct hugetlb_cgroup *h_cg)
 232 {
 233         unsigned long csize = nr_pages * PAGE_SIZE;
 234
 235         if (hugetlb_cgroup_disabled() || !h_cg)
 236                 return;
 237
 238         if (huge_page_order(&hstates[idx]) < HUGETLB_CGROUP_MIN_ORDER)
 239                 return;
 240
 241         res_counter_uncharge(&h_cg->hugepage[idx], csize);
 242         return;
 243 }
 244
 245 static ssize_t hugetlb_cgroup_read(struct cgroup_subsys_state *css,
 246                                    struct cftype *cft, struct file *file,
 247                                    char __user *buf, size_t nbytes,
 248                                    loff_t *ppos)
 249 {
 250         u64 val;
 251         char str[64];
 252         int idx, name, len;
 253         struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_css(css);
 254
 255         idx = MEMFILE_IDX(cft->private);
 256         name = MEMFILE_ATTR(cft->private);
 257
 258         val = res_counter_read_u64(&h_cg->hugepage[idx], name);
 259         len = scnprintf(str, sizeof(str), "%llu\n", (unsigned long long)val);
 260         return simple_read_from_buffer(buf, nbytes, ppos, str, len);
 261 }
 262
 263 static int hugetlb_cgroup_write(struct cgroup_subsys_state *css,
 264                                 struct cftype *cft, const char *buffer)
 265 {
 266         int idx, name, ret;
 267         unsigned long long val;
 268         struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_css(css);
 269
 270         idx = MEMFILE_IDX(cft->private);
 271         name = MEMFILE_ATTR(cft->private);
 272
 273         switch (name) {
 274         case RES_LIMIT:
 275                 if (hugetlb_cgroup_is_root(h_cg)) {
 276                         /* Can't set limit on root */
 277                         ret = -EINVAL;
 278                         break;
 279                 }
 280                 /* This function does all necessary parse...reuse it */
 281                 ret = res_counter_memparse_write_strategy(buffer, &val);
 282                 if (ret)
 283                         break;
 284                 ret = res_counter_set_limit(&h_cg->hugepage[idx], val);
 285                 break;
 286         default:
 287                 ret = -EINVAL;
 288                 break;
 289         }
 290         return ret;
 291 }
 292
 293 static int hugetlb_cgroup_reset(struct cgroup_subsys_state *css,
 294                                 unsigned int event)
 295 {
 296         int idx, name, ret = 0;
 297         struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_css(css);
 298
 299         idx = MEMFILE_IDX(event);
 300         name = MEMFILE_ATTR(event);
 301
 302         switch (name) {
 303         case RES_MAX_USAGE:
 304                 res_counter_reset_max(&h_cg->hugepage[idx]);
 305                 break;
 306         case RES_FAILCNT:
 307                 res_counter_reset_failcnt(&h_cg->hugepage[idx]);
 308                 break;
 309         default:
 310                 ret = -EINVAL;
 311                 break;
 312         }
 313         return ret;
 314 }
 315
 316 static char *mem_fmt(char *buf, int size, unsigned long hsize)
 317 {
 318         if (hsize >= (1UL << 30))
 319                 snprintf(buf, size, "%luGB", hsize >> 30);
 320         else if (hsize >= (1UL << 20))
 321                 snprintf(buf, size, "%luMB", hsize >> 20);
 322         else
 323                 snprintf(buf, size, "%luKB", hsize >> 10);
 324         return buf;
 325 }
 326
 327 static void __init __hugetlb_cgroup_file_init(int idx)
 328 {
 329         char buf[32];
 330         struct cftype *cft;
 331         struct hstate *h = &hstates[idx];
 332
 333         /* format the size */
 334         mem_fmt(buf, 32, huge_page_size(h));
 335
 336         /* Add the limit file */
 337         cft = &h->cgroup_files[0];
 338         snprintf(cft->name, MAX_CFTYPE_NAME, "%s.limit_in_bytes", buf);
 339         cft->private = MEMFILE_PRIVATE(idx, RES_LIMIT);
 340         cft->read = hugetlb_cgroup_read;
 341         cft->write_string = hugetlb_cgroup_write;
 342
 343         /* Add the usage file */
 344         cft = &h->cgroup_files[1];
 345         snprintf(cft->name, MAX_CFTYPE_NAME, "%s.usage_in_bytes", buf);
 346         cft->private = MEMFILE_PRIVATE(idx, RES_USAGE);
 347         cft->read = hugetlb_cgroup_read;
 348
 349         /* Add the MAX usage file */
 350         cft = &h->cgroup_files[2];
 351         snprintf(cft->name, MAX_CFTYPE_NAME, "%s.max_usage_in_bytes", buf);
 352         cft->private = MEMFILE_PRIVATE(idx, RES_MAX_USAGE);
 353         cft->trigger = hugetlb_cgroup_reset;
 354         cft->read = hugetlb_cgroup_read;
 355
 356         /* Add the failcntfile */
 357         cft = &h->cgroup_files[3];
 358         snprintf(cft->name, MAX_CFTYPE_NAME, "%s.failcnt", buf);
 359         cft->private  = MEMFILE_PRIVATE(idx, RES_FAILCNT);
 360         cft->trigger  = hugetlb_cgroup_reset;
 361         cft->read = hugetlb_cgroup_read;
 362
 363         /* NULL terminate the last cft */
 364         cft = &h->cgroup_files[4];
 365         memset(cft, 0, sizeof(*cft));
 366
 367         WARN_ON(cgroup_add_cftypes(&hugetlb_subsys, h->cgroup_files));
 368
 369         return;
 370 }
 371
 372 void __init hugetlb_cgroup_file_init(void)
 373 {
 374         struct hstate *h;
 375
 376         for_each_hstate(h) {
 377                 /*
 378                  * Add cgroup control files only if the huge page consists
 379                  * of more than two normal pages. This is because we use
 380                  * page[2].lru.next for storing cgroup details.
 381                  */
 382                 if (huge_page_order(h) >= HUGETLB_CGROUP_MIN_ORDER)
 383                         __hugetlb_cgroup_file_init(hstate_index(h));
 384         }
 385 }
 386
 387 /*
 388  * hugetlb_lock will make sure a parallel cgroup rmdir won't happen
 389  * when we migrate hugepages
 390  */
 391 void hugetlb_cgroup_migrate(struct page *oldhpage, struct page *newhpage)
 392 {
 393         struct hugetlb_cgroup *h_cg;
 394         struct hstate *h = page_hstate(oldhpage);
 395
 396         if (hugetlb_cgroup_disabled())
 397                 return;
 398
 399         VM_BUG_ON(!PageHuge(oldhpage));
 400         spin_lock(&hugetlb_lock);
 401         h_cg = hugetlb_cgroup_from_page(oldhpage);
 402         set_hugetlb_cgroup(oldhpage, NULL);
 403
 404         /* move the h_cg details to new cgroup */
 405         set_hugetlb_cgroup(newhpage, h_cg);
 406         list_move(&newhpage->lru, &h->hugepage_activelist);
 407         spin_unlock(&hugetlb_lock);
 408         return;
 409 }
 410
 411 struct cgroup_subsys hugetlb_subsys = {
 412         .name = "hugetlb",
 413         .css_alloc      = hugetlb_cgroup_css_alloc,
 414         .css_offline    = hugetlb_cgroup_css_offline,
 415         .css_free       = hugetlb_cgroup_css_free,
 416         .subsys_id      = hugetlb_subsys_id,
 417 };