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/slab.h>
  18#include <linux/hugetlb.h>
  19#include <linux/hugetlb_cgroup.h>
  20
  21struct 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
  33struct cgroup_subsys hugetlb_subsys __read_mostly;
  34static struct hugetlb_cgroup *root_h_cgroup __read_mostly;
  35
  36static inline
  37struct 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
  42static inline
  43struct 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
  48static inline bool hugetlb_cgroup_is_root(struct hugetlb_cgroup *h_cg)
  49{
  50        return (h_cg == root_h_cgroup);
  51}
  52
  53static inline struct hugetlb_cgroup *
  54parent_hugetlb_cgroup(struct hugetlb_cgroup *h_cg)
  55{
  56        return hugetlb_cgroup_from_css(css_parent(&h_cg->css));
  57}
  58
  59static 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
  70static struct cgroup_subsys_state *
  71hugetlb_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
  93static 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 */
 109static 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);
 138out:
 139        return;
 140}
 141
 142/*
 143 * Force the hugetlb cgroup to empty the hugetlb resources by moving them to
 144 * the parent cgroup.
 145 */
 146static 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
 166int 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;
 182again:
 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);
 193done:
 194        *ptr = h_cg;
 195        return ret;
 196}
 197
 198/* Should be called with hugetlb_lock held */
 199void 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 */
 213void 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
 230void 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
 245static 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
 263static 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
 293static 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
 316static 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
 327static 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
 372void __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 */
 391void 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
 411struct 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};
 418
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