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
  22struct 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
  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_cgrp_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(h_cg->css.parent);
  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 (page_counter_read(&h_cg->hugepage[idx]))
  65                        return true;
  66        }
  67        return false;
  68}
  69
  70static void hugetlb_cgroup_init(struct hugetlb_cgroup *h_cgroup,
  71                                struct hugetlb_cgroup *parent_h_cgroup)
  72{
  73        int idx;
  74
  75        for (idx = 0; idx < HUGE_MAX_HSTATE; idx++) {
  76                struct page_counter *counter = &h_cgroup->hugepage[idx];
  77                struct page_counter *parent = NULL;
  78                unsigned long limit;
  79                int ret;
  80
  81                if (parent_h_cgroup)
  82                        parent = &parent_h_cgroup->hugepage[idx];
  83                page_counter_init(counter, parent);
  84
  85                limit = round_down(PAGE_COUNTER_MAX,
  86                                   1 << huge_page_order(&hstates[idx]));
  87                ret = page_counter_set_max(counter, limit);
  88                VM_BUG_ON(ret);
  89        }
  90}
  91
  92static struct cgroup_subsys_state *
  93hugetlb_cgroup_css_alloc(struct cgroup_subsys_state *parent_css)
  94{
  95        struct hugetlb_cgroup *parent_h_cgroup = hugetlb_cgroup_from_css(parent_css);
  96        struct hugetlb_cgroup *h_cgroup;
  97
  98        h_cgroup = kzalloc(sizeof(*h_cgroup), GFP_KERNEL);
  99        if (!h_cgroup)
 100                return ERR_PTR(-ENOMEM);
 101
 102        if (!parent_h_cgroup)
 103                root_h_cgroup = h_cgroup;
 104
 105        hugetlb_cgroup_init(h_cgroup, parent_h_cgroup);
 106        return &h_cgroup->css;
 107}
 108
 109static void hugetlb_cgroup_css_free(struct cgroup_subsys_state *css)
 110{
 111        struct hugetlb_cgroup *h_cgroup;
 112
 113        h_cgroup = hugetlb_cgroup_from_css(css);
 114        kfree(h_cgroup);
 115}
 116
 117
 118/*
 119 * Should be called with hugetlb_lock held.
 120 * Since we are holding hugetlb_lock, pages cannot get moved from
 121 * active list or uncharged from the cgroup, So no need to get
 122 * page reference and test for page active here. This function
 123 * cannot fail.
 124 */
 125static void hugetlb_cgroup_move_parent(int idx, struct hugetlb_cgroup *h_cg,
 126                                       struct page *page)
 127{
 128        unsigned int nr_pages;
 129        struct page_counter *counter;
 130        struct hugetlb_cgroup *page_hcg;
 131        struct hugetlb_cgroup *parent = parent_hugetlb_cgroup(h_cg);
 132
 133        page_hcg = hugetlb_cgroup_from_page(page);
 134        /*
 135         * We can have pages in active list without any cgroup
 136         * ie, hugepage with less than 3 pages. We can safely
 137         * ignore those pages.
 138         */
 139        if (!page_hcg || page_hcg != h_cg)
 140                goto out;
 141
 142        nr_pages = 1 << compound_order(page);
 143        if (!parent) {
 144                parent = root_h_cgroup;
 145                /* root has no limit */
 146                page_counter_charge(&parent->hugepage[idx], nr_pages);
 147        }
 148        counter = &h_cg->hugepage[idx];
 149        /* Take the pages off the local counter */
 150        page_counter_cancel(counter, nr_pages);
 151
 152        set_hugetlb_cgroup(page, parent);
 153out:
 154        return;
 155}
 156
 157/*
 158 * Force the hugetlb cgroup to empty the hugetlb resources by moving them to
 159 * the parent cgroup.
 160 */
 161static void hugetlb_cgroup_css_offline(struct cgroup_subsys_state *css)
 162{
 163        struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_css(css);
 164        struct hstate *h;
 165        struct page *page;
 166        int idx = 0;
 167
 168        do {
 169                for_each_hstate(h) {
 170                        spin_lock(&hugetlb_lock);
 171                        list_for_each_entry(page, &h->hugepage_activelist, lru)
 172                                hugetlb_cgroup_move_parent(idx, h_cg, page);
 173
 174                        spin_unlock(&hugetlb_lock);
 175                        idx++;
 176                }
 177                cond_resched();
 178        } while (hugetlb_cgroup_have_usage(h_cg));
 179}
 180
 181int hugetlb_cgroup_charge_cgroup(int idx, unsigned long nr_pages,
 182                                 struct hugetlb_cgroup **ptr)
 183{
 184        int ret = 0;
 185        struct page_counter *counter;
 186        struct hugetlb_cgroup *h_cg = NULL;
 187
 188        if (hugetlb_cgroup_disabled())
 189                goto done;
 190        /*
 191         * We don't charge any cgroup if the compound page have less
 192         * than 3 pages.
 193         */
 194        if (huge_page_order(&hstates[idx]) < HUGETLB_CGROUP_MIN_ORDER)
 195                goto done;
 196again:
 197        rcu_read_lock();
 198        h_cg = hugetlb_cgroup_from_task(current);
 199        if (!css_tryget_online(&h_cg->css)) {
 200                rcu_read_unlock();
 201                goto again;
 202        }
 203        rcu_read_unlock();
 204
 205        if (!page_counter_try_charge(&h_cg->hugepage[idx], nr_pages, &counter))
 206                ret = -ENOMEM;
 207        css_put(&h_cg->css);
 208done:
 209        *ptr = h_cg;
 210        return ret;
 211}
 212
 213/* Should be called with hugetlb_lock held */
 214void hugetlb_cgroup_commit_charge(int idx, unsigned long nr_pages,
 215                                  struct hugetlb_cgroup *h_cg,
 216                                  struct page *page)
 217{
 218        if (hugetlb_cgroup_disabled() || !h_cg)
 219                return;
 220
 221        set_hugetlb_cgroup(page, h_cg);
 222        return;
 223}
 224
 225/*
 226 * Should be called with hugetlb_lock held
 227 */
 228void hugetlb_cgroup_uncharge_page(int idx, unsigned long nr_pages,
 229                                  struct page *page)
 230{
 231        struct hugetlb_cgroup *h_cg;
 232
 233        if (hugetlb_cgroup_disabled())
 234                return;
 235        lockdep_assert_held(&hugetlb_lock);
 236        h_cg = hugetlb_cgroup_from_page(page);
 237        if (unlikely(!h_cg))
 238                return;
 239        set_hugetlb_cgroup(page, NULL);
 240        page_counter_uncharge(&h_cg->hugepage[idx], nr_pages);
 241        return;
 242}
 243
 244void hugetlb_cgroup_uncharge_cgroup(int idx, unsigned long nr_pages,
 245                                    struct hugetlb_cgroup *h_cg)
 246{
 247        if (hugetlb_cgroup_disabled() || !h_cg)
 248                return;
 249
 250        if (huge_page_order(&hstates[idx]) < HUGETLB_CGROUP_MIN_ORDER)
 251                return;
 252
 253        page_counter_uncharge(&h_cg->hugepage[idx], nr_pages);
 254        return;
 255}
 256
 257enum {
 258        RES_USAGE,
 259        RES_LIMIT,
 260        RES_MAX_USAGE,
 261        RES_FAILCNT,
 262};
 263
 264static u64 hugetlb_cgroup_read_u64(struct cgroup_subsys_state *css,
 265                                   struct cftype *cft)
 266{
 267        struct page_counter *counter;
 268        struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_css(css);
 269
 270        counter = &h_cg->hugepage[MEMFILE_IDX(cft->private)];
 271
 272        switch (MEMFILE_ATTR(cft->private)) {
 273        case RES_USAGE:
 274                return (u64)page_counter_read(counter) * PAGE_SIZE;
 275        case RES_LIMIT:
 276                return (u64)counter->max * PAGE_SIZE;
 277        case RES_MAX_USAGE:
 278                return (u64)counter->watermark * PAGE_SIZE;
 279        case RES_FAILCNT:
 280                return counter->failcnt;
 281        default:
 282                BUG();
 283        }
 284}
 285
 286static DEFINE_MUTEX(hugetlb_limit_mutex);
 287
 288static ssize_t hugetlb_cgroup_write(struct kernfs_open_file *of,
 289                                    char *buf, size_t nbytes, loff_t off)
 290{
 291        int ret, idx;
 292        unsigned long nr_pages;
 293        struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_css(of_css(of));
 294
 295        if (hugetlb_cgroup_is_root(h_cg)) /* Can't set limit on root */
 296                return -EINVAL;
 297
 298        buf = strstrip(buf);
 299        ret = page_counter_memparse(buf, "-1", &nr_pages);
 300        if (ret)
 301                return ret;
 302
 303        idx = MEMFILE_IDX(of_cft(of)->private);
 304        nr_pages = round_down(nr_pages, 1 << huge_page_order(&hstates[idx]));
 305
 306        switch (MEMFILE_ATTR(of_cft(of)->private)) {
 307        case RES_LIMIT:
 308                mutex_lock(&hugetlb_limit_mutex);
 309                ret = page_counter_set_max(&h_cg->hugepage[idx], nr_pages);
 310                mutex_unlock(&hugetlb_limit_mutex);
 311                break;
 312        default:
 313                ret = -EINVAL;
 314                break;
 315        }
 316        return ret ?: nbytes;
 317}
 318
 319static ssize_t hugetlb_cgroup_reset(struct kernfs_open_file *of,
 320                                    char *buf, size_t nbytes, loff_t off)
 321{
 322        int ret = 0;
 323        struct page_counter *counter;
 324        struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_css(of_css(of));
 325
 326        counter = &h_cg->hugepage[MEMFILE_IDX(of_cft(of)->private)];
 327
 328        switch (MEMFILE_ATTR(of_cft(of)->private)) {
 329        case RES_MAX_USAGE:
 330                page_counter_reset_watermark(counter);
 331                break;
 332        case RES_FAILCNT:
 333                counter->failcnt = 0;
 334                break;
 335        default:
 336                ret = -EINVAL;
 337                break;
 338        }
 339        return ret ?: nbytes;
 340}
 341
 342static char *mem_fmt(char *buf, int size, unsigned long hsize)
 343{
 344        if (hsize >= (1UL << 30))
 345                snprintf(buf, size, "%luGB", hsize >> 30);
 346        else if (hsize >= (1UL << 20))
 347                snprintf(buf, size, "%luMB", hsize >> 20);
 348        else
 349                snprintf(buf, size, "%luKB", hsize >> 10);
 350        return buf;
 351}
 352
 353static void __init __hugetlb_cgroup_file_init(int idx)
 354{
 355        char buf[32];
 356        struct cftype *cft;
 357        struct hstate *h = &hstates[idx];
 358
 359        /* format the size */
 360        mem_fmt(buf, 32, huge_page_size(h));
 361
 362        /* Add the limit file */
 363        cft = &h->cgroup_files[0];
 364        snprintf(cft->name, MAX_CFTYPE_NAME, "%s.limit_in_bytes", buf);
 365        cft->private = MEMFILE_PRIVATE(idx, RES_LIMIT);
 366        cft->read_u64 = hugetlb_cgroup_read_u64;
 367        cft->write = hugetlb_cgroup_write;
 368
 369        /* Add the usage file */
 370        cft = &h->cgroup_files[1];
 371        snprintf(cft->name, MAX_CFTYPE_NAME, "%s.usage_in_bytes", buf);
 372        cft->private = MEMFILE_PRIVATE(idx, RES_USAGE);
 373        cft->read_u64 = hugetlb_cgroup_read_u64;
 374
 375        /* Add the MAX usage file */
 376        cft = &h->cgroup_files[2];
 377        snprintf(cft->name, MAX_CFTYPE_NAME, "%s.max_usage_in_bytes", buf);
 378        cft->private = MEMFILE_PRIVATE(idx, RES_MAX_USAGE);
 379        cft->write = hugetlb_cgroup_reset;
 380        cft->read_u64 = hugetlb_cgroup_read_u64;
 381
 382        /* Add the failcntfile */
 383        cft = &h->cgroup_files[3];
 384        snprintf(cft->name, MAX_CFTYPE_NAME, "%s.failcnt", buf);
 385        cft->private  = MEMFILE_PRIVATE(idx, RES_FAILCNT);
 386        cft->write = hugetlb_cgroup_reset;
 387        cft->read_u64 = hugetlb_cgroup_read_u64;
 388
 389        /* NULL terminate the last cft */
 390        cft = &h->cgroup_files[4];
 391        memset(cft, 0, sizeof(*cft));
 392
 393        WARN_ON(cgroup_add_legacy_cftypes(&hugetlb_cgrp_subsys,
 394                                          h->cgroup_files));
 395}
 396
 397void __init hugetlb_cgroup_file_init(void)
 398{
 399        struct hstate *h;
 400
 401        for_each_hstate(h) {
 402                /*
 403                 * Add cgroup control files only if the huge page consists
 404                 * of more than two normal pages. This is because we use
 405                 * page[2].private for storing cgroup details.
 406                 */
 407                if (huge_page_order(h) >= HUGETLB_CGROUP_MIN_ORDER)
 408                        __hugetlb_cgroup_file_init(hstate_index(h));
 409        }
 410}
 411
 412/*
 413 * hugetlb_lock will make sure a parallel cgroup rmdir won't happen
 414 * when we migrate hugepages
 415 */
 416void hugetlb_cgroup_migrate(struct page *oldhpage, struct page *newhpage)
 417{
 418        struct hugetlb_cgroup *h_cg;
 419        struct hstate *h = page_hstate(oldhpage);
 420
 421        if (hugetlb_cgroup_disabled())
 422                return;
 423
 424        VM_BUG_ON_PAGE(!PageHuge(oldhpage), oldhpage);
 425        spin_lock(&hugetlb_lock);
 426        h_cg = hugetlb_cgroup_from_page(oldhpage);
 427        set_hugetlb_cgroup(oldhpage, NULL);
 428
 429        /* move the h_cg details to new cgroup */
 430        set_hugetlb_cgroup(newhpage, h_cg);
 431        list_move(&newhpage->lru, &h->hugepage_activelist);
 432        spin_unlock(&hugetlb_lock);
 433        return;
 434}
 435
 436struct cgroup_subsys hugetlb_cgrp_subsys = {
 437        .css_alloc      = hugetlb_cgroup_css_alloc,
 438        .css_offline    = hugetlb_cgroup_css_offline,
 439        .css_free       = hugetlb_cgroup_css_free,
 440};
 441