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 container_of(s, struct hugetlb_cgroup, css);
  40}
  41
  42static inline
  43struct hugetlb_cgroup *hugetlb_cgroup_from_cgroup(struct cgroup *cgroup)
  44{
  45        return hugetlb_cgroup_from_css(cgroup_subsys_state(cgroup,
  46                                                           hugetlb_subsys_id));
  47}
  48
  49static inline
  50struct hugetlb_cgroup *hugetlb_cgroup_from_task(struct task_struct *task)
  51{
  52        return hugetlb_cgroup_from_css(task_subsys_state(task,
  53                                                         hugetlb_subsys_id));
  54}
  55
  56static inline bool hugetlb_cgroup_is_root(struct hugetlb_cgroup *h_cg)
  57{
  58        return (h_cg == root_h_cgroup);
  59}
  60
  61static inline struct hugetlb_cgroup *parent_hugetlb_cgroup(struct cgroup *cg)
  62{
  63        if (!cg->parent)
  64                return NULL;
  65        return hugetlb_cgroup_from_cgroup(cg->parent);
  66}
  67
  68static inline bool hugetlb_cgroup_have_usage(struct cgroup *cg)
  69{
  70        int idx;
  71        struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_cgroup(cg);
  72
  73        for (idx = 0; idx < hugetlb_max_hstate; idx++) {
  74                if ((res_counter_read_u64(&h_cg->hugepage[idx], RES_USAGE)) > 0)
  75                        return true;
  76        }
  77        return false;
  78}
  79
  80static struct cgroup_subsys_state *hugetlb_cgroup_css_alloc(struct cgroup *cgroup)
  81{
  82        int idx;
  83        struct cgroup *parent_cgroup;
  84        struct hugetlb_cgroup *h_cgroup, *parent_h_cgroup;
  85
  86        h_cgroup = kzalloc(sizeof(*h_cgroup), GFP_KERNEL);
  87        if (!h_cgroup)
  88                return ERR_PTR(-ENOMEM);
  89
  90        parent_cgroup = cgroup->parent;
  91        if (parent_cgroup) {
  92                parent_h_cgroup = hugetlb_cgroup_from_cgroup(parent_cgroup);
  93                for (idx = 0; idx < HUGE_MAX_HSTATE; idx++)
  94                        res_counter_init(&h_cgroup->hugepage[idx],
  95                                         &parent_h_cgroup->hugepage[idx]);
  96        } else {
  97                root_h_cgroup = h_cgroup;
  98                for (idx = 0; idx < HUGE_MAX_HSTATE; idx++)
  99                        res_counter_init(&h_cgroup->hugepage[idx], NULL);
 100        }
 101        return &h_cgroup->css;
 102}
 103
 104static void hugetlb_cgroup_css_free(struct cgroup *cgroup)
 105{
 106        struct hugetlb_cgroup *h_cgroup;
 107
 108        h_cgroup = hugetlb_cgroup_from_cgroup(cgroup);
 109        kfree(h_cgroup);
 110}
 111
 112
 113/*
 114 * Should be called with hugetlb_lock held.
 115 * Since we are holding hugetlb_lock, pages cannot get moved from
 116 * active list or uncharged from the cgroup, So no need to get
 117 * page reference and test for page active here. This function
 118 * cannot fail.
 119 */
 120static void hugetlb_cgroup_move_parent(int idx, struct cgroup *cgroup,
 121                                       struct page *page)
 122{
 123        int csize;
 124        struct res_counter *counter;
 125        struct res_counter *fail_res;
 126        struct hugetlb_cgroup *page_hcg;
 127        struct hugetlb_cgroup *h_cg   = hugetlb_cgroup_from_cgroup(cgroup);
 128        struct hugetlb_cgroup *parent = parent_hugetlb_cgroup(cgroup);
 129
 130        page_hcg = hugetlb_cgroup_from_page(page);
 131        /*
 132         * We can have pages in active list without any cgroup
 133         * ie, hugepage with less than 3 pages. We can safely
 134         * ignore those pages.
 135         */
 136        if (!page_hcg || page_hcg != h_cg)
 137                goto out;
 138
 139        csize = PAGE_SIZE << compound_order(page);
 140        if (!parent) {
 141                parent = root_h_cgroup;
 142                /* root has no limit */
 143                res_counter_charge_nofail(&parent->hugepage[idx],
 144                                          csize, &fail_res);
 145        }
 146        counter = &h_cg->hugepage[idx];
 147        res_counter_uncharge_until(counter, counter->parent, csize);
 148
 149        set_hugetlb_cgroup(page, parent);
 150out:
 151        return;
 152}
 153
 154/*
 155 * Force the hugetlb cgroup to empty the hugetlb resources by moving them to
 156 * the parent cgroup.
 157 */
 158static void hugetlb_cgroup_css_offline(struct cgroup *cgroup)
 159{
 160        struct hstate *h;
 161        struct page *page;
 162        int idx = 0;
 163
 164        do {
 165                for_each_hstate(h) {
 166                        spin_lock(&hugetlb_lock);
 167                        list_for_each_entry(page, &h->hugepage_activelist, lru)
 168                                hugetlb_cgroup_move_parent(idx, cgroup, page);
 169
 170                        spin_unlock(&hugetlb_lock);
 171                        idx++;
 172                }
 173                cond_resched();
 174        } while (hugetlb_cgroup_have_usage(cgroup));
 175}
 176
 177int hugetlb_cgroup_charge_cgroup(int idx, unsigned long nr_pages,
 178                                 struct hugetlb_cgroup **ptr)
 179{
 180        int ret = 0;
 181        struct res_counter *fail_res;
 182        struct hugetlb_cgroup *h_cg = NULL;
 183        unsigned long csize = nr_pages * PAGE_SIZE;
 184
 185        if (hugetlb_cgroup_disabled())
 186                goto done;
 187        /*
 188         * We don't charge any cgroup if the compound page have less
 189         * than 3 pages.
 190         */
 191        if (huge_page_order(&hstates[idx]) < HUGETLB_CGROUP_MIN_ORDER)
 192                goto done;
 193again:
 194        rcu_read_lock();
 195        h_cg = hugetlb_cgroup_from_task(current);
 196        if (!css_tryget(&h_cg->css)) {
 197                rcu_read_unlock();
 198                goto again;
 199        }
 200        rcu_read_unlock();
 201
 202        ret = res_counter_charge(&h_cg->hugepage[idx], csize, &fail_res);
 203        css_put(&h_cg->css);
 204done:
 205        *ptr = h_cg;
 206        return ret;
 207}
 208
 209/* Should be called with hugetlb_lock held */
 210void hugetlb_cgroup_commit_charge(int idx, unsigned long nr_pages,
 211                                  struct hugetlb_cgroup *h_cg,
 212                                  struct page *page)
 213{
 214        if (hugetlb_cgroup_disabled() || !h_cg)
 215                return;
 216
 217        set_hugetlb_cgroup(page, h_cg);
 218        return;
 219}
 220
 221/*
 222 * Should be called with hugetlb_lock held
 223 */
 224void hugetlb_cgroup_uncharge_page(int idx, unsigned long nr_pages,
 225                                  struct page *page)
 226{
 227        struct hugetlb_cgroup *h_cg;
 228        unsigned long csize = nr_pages * PAGE_SIZE;
 229
 230        if (hugetlb_cgroup_disabled())
 231                return;
 232        VM_BUG_ON(!spin_is_locked(&hugetlb_lock));
 233        h_cg = hugetlb_cgroup_from_page(page);
 234        if (unlikely(!h_cg))
 235                return;
 236        set_hugetlb_cgroup(page, NULL);
 237        res_counter_uncharge(&h_cg->hugepage[idx], csize);
 238        return;
 239}
 240
 241void hugetlb_cgroup_uncharge_cgroup(int idx, unsigned long nr_pages,
 242                                    struct hugetlb_cgroup *h_cg)
 243{
 244        unsigned long csize = nr_pages * PAGE_SIZE;
 245
 246        if (hugetlb_cgroup_disabled() || !h_cg)
 247                return;
 248
 249        if (huge_page_order(&hstates[idx]) < HUGETLB_CGROUP_MIN_ORDER)
 250                return;
 251
 252        res_counter_uncharge(&h_cg->hugepage[idx], csize);
 253        return;
 254}
 255
 256static ssize_t hugetlb_cgroup_read(struct cgroup *cgroup, struct cftype *cft,
 257                                   struct file *file, char __user *buf,
 258                                   size_t nbytes, loff_t *ppos)
 259{
 260        u64 val;
 261        char str[64];
 262        int idx, name, len;
 263        struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_cgroup(cgroup);
 264
 265        idx = MEMFILE_IDX(cft->private);
 266        name = MEMFILE_ATTR(cft->private);
 267
 268        val = res_counter_read_u64(&h_cg->hugepage[idx], name);
 269        len = scnprintf(str, sizeof(str), "%llu\n", (unsigned long long)val);
 270        return simple_read_from_buffer(buf, nbytes, ppos, str, len);
 271}
 272
 273static int hugetlb_cgroup_write(struct cgroup *cgroup, struct cftype *cft,
 274                                const char *buffer)
 275{
 276        int idx, name, ret;
 277        unsigned long long val;
 278        struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_cgroup(cgroup);
 279
 280        idx = MEMFILE_IDX(cft->private);
 281        name = MEMFILE_ATTR(cft->private);
 282
 283        switch (name) {
 284        case RES_LIMIT:
 285                if (hugetlb_cgroup_is_root(h_cg)) {
 286                        /* Can't set limit on root */
 287                        ret = -EINVAL;
 288                        break;
 289                }
 290                /* This function does all necessary parse...reuse it */
 291                ret = res_counter_memparse_write_strategy(buffer, &val);
 292                if (ret)
 293                        break;
 294                ret = res_counter_set_limit(&h_cg->hugepage[idx], val);
 295                break;
 296        default:
 297                ret = -EINVAL;
 298                break;
 299        }
 300        return ret;
 301}
 302
 303static int hugetlb_cgroup_reset(struct cgroup *cgroup, unsigned int event)
 304{
 305        int idx, name, ret = 0;
 306        struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_cgroup(cgroup);
 307
 308        idx = MEMFILE_IDX(event);
 309        name = MEMFILE_ATTR(event);
 310
 311        switch (name) {
 312        case RES_MAX_USAGE:
 313                res_counter_reset_max(&h_cg->hugepage[idx]);
 314                break;
 315        case RES_FAILCNT:
 316                res_counter_reset_failcnt(&h_cg->hugepage[idx]);
 317                break;
 318        default:
 319                ret = -EINVAL;
 320                break;
 321        }
 322        return ret;
 323}
 324
 325static char *mem_fmt(char *buf, int size, unsigned long hsize)
 326{
 327        if (hsize >= (1UL << 30))
 328                snprintf(buf, size, "%luGB", hsize >> 30);
 329        else if (hsize >= (1UL << 20))
 330                snprintf(buf, size, "%luMB", hsize >> 20);
 331        else
 332                snprintf(buf, size, "%luKB", hsize >> 10);
 333        return buf;
 334}
 335
 336static void __init __hugetlb_cgroup_file_init(int idx)
 337{
 338        char buf[32];
 339        struct cftype *cft;
 340        struct hstate *h = &hstates[idx];
 341
 342        /* format the size */
 343        mem_fmt(buf, 32, huge_page_size(h));
 344
 345        /* Add the limit file */
 346        cft = &h->cgroup_files[0];
 347        snprintf(cft->name, MAX_CFTYPE_NAME, "%s.limit_in_bytes", buf);
 348        cft->private = MEMFILE_PRIVATE(idx, RES_LIMIT);
 349        cft->read = hugetlb_cgroup_read;
 350        cft->write_string = hugetlb_cgroup_write;
 351
 352        /* Add the usage file */
 353        cft = &h->cgroup_files[1];
 354        snprintf(cft->name, MAX_CFTYPE_NAME, "%s.usage_in_bytes", buf);
 355        cft->private = MEMFILE_PRIVATE(idx, RES_USAGE);
 356        cft->read = hugetlb_cgroup_read;
 357
 358        /* Add the MAX usage file */
 359        cft = &h->cgroup_files[2];
 360        snprintf(cft->name, MAX_CFTYPE_NAME, "%s.max_usage_in_bytes", buf);
 361        cft->private = MEMFILE_PRIVATE(idx, RES_MAX_USAGE);
 362        cft->trigger = hugetlb_cgroup_reset;
 363        cft->read = hugetlb_cgroup_read;
 364
 365        /* Add the failcntfile */
 366        cft = &h->cgroup_files[3];
 367        snprintf(cft->name, MAX_CFTYPE_NAME, "%s.failcnt", buf);
 368        cft->private  = MEMFILE_PRIVATE(idx, RES_FAILCNT);
 369        cft->trigger  = hugetlb_cgroup_reset;
 370        cft->read = hugetlb_cgroup_read;
 371
 372        /* NULL terminate the last cft */
 373        cft = &h->cgroup_files[4];
 374        memset(cft, 0, sizeof(*cft));
 375
 376        WARN_ON(cgroup_add_cftypes(&hugetlb_subsys, h->cgroup_files));
 377
 378        return;
 379}
 380
 381void __init hugetlb_cgroup_file_init(void)
 382{
 383        struct hstate *h;
 384
 385        for_each_hstate(h) {
 386                /*
 387                 * Add cgroup control files only if the huge page consists
 388                 * of more than two normal pages. This is because we use
 389                 * page[2].lru.next for storing cgroup details.
 390                 */
 391                if (huge_page_order(h) >= HUGETLB_CGROUP_MIN_ORDER)
 392                        __hugetlb_cgroup_file_init(hstate_index(h));
 393        }
 394}
 395
 396/*
 397 * hugetlb_lock will make sure a parallel cgroup rmdir won't happen
 398 * when we migrate hugepages
 399 */
 400void hugetlb_cgroup_migrate(struct page *oldhpage, struct page *newhpage)
 401{
 402        struct hugetlb_cgroup *h_cg;
 403        struct hstate *h = page_hstate(oldhpage);
 404
 405        if (hugetlb_cgroup_disabled())
 406                return;
 407
 408        VM_BUG_ON(!PageHuge(oldhpage));
 409        spin_lock(&hugetlb_lock);
 410        h_cg = hugetlb_cgroup_from_page(oldhpage);
 411        set_hugetlb_cgroup(oldhpage, NULL);
 412
 413        /* move the h_cg details to new cgroup */
 414        set_hugetlb_cgroup(newhpage, h_cg);
 415        list_move(&newhpage->lru, &h->hugepage_activelist);
 416        spin_unlock(&hugetlb_lock);
 417        return;
 418}
 419
 420struct cgroup_subsys hugetlb_subsys = {
 421        .name = "hugetlb",
 422        .css_alloc      = hugetlb_cgroup_css_alloc,
 423        .css_offline    = hugetlb_cgroup_css_offline,
 424        .css_free       = hugetlb_cgroup_css_free,
 425        .subsys_id      = hugetlb_subsys_id,
 426};
 427
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