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_create(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_destroy(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 int hugetlb_cgroup_pre_destroy(struct cgroup *cgroup)
 159{
 160        struct hstate *h;
 161        struct page *page;
 162        int ret = 0, idx = 0;
 163
 164        do {
 165                if (cgroup_task_count(cgroup) ||
 166                    !list_empty(&cgroup->children)) {
 167                        ret = -EBUSY;
 168                        goto out;
 169                }
 170                for_each_hstate(h) {
 171                        spin_lock(&hugetlb_lock);
 172                        list_for_each_entry(page, &h->hugepage_activelist, lru)
 173                                hugetlb_cgroup_move_parent(idx, cgroup, page);
 174
 175                        spin_unlock(&hugetlb_lock);
 176                        idx++;
 177                }
 178                cond_resched();
 179        } while (hugetlb_cgroup_have_usage(cgroup));
 180out:
 181        return ret;
 182}
 183
 184int hugetlb_cgroup_charge_cgroup(int idx, unsigned long nr_pages,
 185                                 struct hugetlb_cgroup **ptr)
 186{
 187        int ret = 0;
 188        struct res_counter *fail_res;
 189        struct hugetlb_cgroup *h_cg = NULL;
 190        unsigned long csize = nr_pages * PAGE_SIZE;
 191
 192        if (hugetlb_cgroup_disabled())
 193                goto done;
 194        /*
 195         * We don't charge any cgroup if the compound page have less
 196         * than 3 pages.
 197         */
 198        if (huge_page_order(&hstates[idx]) < HUGETLB_CGROUP_MIN_ORDER)
 199                goto done;
 200again:
 201        rcu_read_lock();
 202        h_cg = hugetlb_cgroup_from_task(current);
 203        if (!css_tryget(&h_cg->css)) {
 204                rcu_read_unlock();
 205                goto again;
 206        }
 207        rcu_read_unlock();
 208
 209        ret = res_counter_charge(&h_cg->hugepage[idx], csize, &fail_res);
 210        css_put(&h_cg->css);
 211done:
 212        *ptr = h_cg;
 213        return ret;
 214}
 215
 216/* Should be called with hugetlb_lock held */
 217void hugetlb_cgroup_commit_charge(int idx, unsigned long nr_pages,
 218                                  struct hugetlb_cgroup *h_cg,
 219                                  struct page *page)
 220{
 221        if (hugetlb_cgroup_disabled() || !h_cg)
 222                return;
 223
 224        set_hugetlb_cgroup(page, h_cg);
 225        return;
 226}
 227
 228/*
 229 * Should be called with hugetlb_lock held
 230 */
 231void hugetlb_cgroup_uncharge_page(int idx, unsigned long nr_pages,
 232                                  struct page *page)
 233{
 234        struct hugetlb_cgroup *h_cg;
 235        unsigned long csize = nr_pages * PAGE_SIZE;
 236
 237        if (hugetlb_cgroup_disabled())
 238                return;
 239        VM_BUG_ON(!spin_is_locked(&hugetlb_lock));
 240        h_cg = hugetlb_cgroup_from_page(page);
 241        if (unlikely(!h_cg))
 242                return;
 243        set_hugetlb_cgroup(page, NULL);
 244        res_counter_uncharge(&h_cg->hugepage[idx], csize);
 245        return;
 246}
 247
 248void hugetlb_cgroup_uncharge_cgroup(int idx, unsigned long nr_pages,
 249                                    struct hugetlb_cgroup *h_cg)
 250{
 251        unsigned long csize = nr_pages * PAGE_SIZE;
 252
 253        if (hugetlb_cgroup_disabled() || !h_cg)
 254                return;
 255
 256        if (huge_page_order(&hstates[idx]) < HUGETLB_CGROUP_MIN_ORDER)
 257                return;
 258
 259        res_counter_uncharge(&h_cg->hugepage[idx], csize);
 260        return;
 261}
 262
 263static ssize_t hugetlb_cgroup_read(struct cgroup *cgroup, struct cftype *cft,
 264                                   struct file *file, char __user *buf,
 265                                   size_t nbytes, loff_t *ppos)
 266{
 267        u64 val;
 268        char str[64];
 269        int idx, name, len;
 270        struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_cgroup(cgroup);
 271
 272        idx = MEMFILE_IDX(cft->private);
 273        name = MEMFILE_ATTR(cft->private);
 274
 275        val = res_counter_read_u64(&h_cg->hugepage[idx], name);
 276        len = scnprintf(str, sizeof(str), "%llu\n", (unsigned long long)val);
 277        return simple_read_from_buffer(buf, nbytes, ppos, str, len);
 278}
 279
 280static int hugetlb_cgroup_write(struct cgroup *cgroup, struct cftype *cft,
 281                                const char *buffer)
 282{
 283        int idx, name, ret;
 284        unsigned long long val;
 285        struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_cgroup(cgroup);
 286
 287        idx = MEMFILE_IDX(cft->private);
 288        name = MEMFILE_ATTR(cft->private);
 289
 290        switch (name) {
 291        case RES_LIMIT:
 292                if (hugetlb_cgroup_is_root(h_cg)) {
 293                        /* Can't set limit on root */
 294                        ret = -EINVAL;
 295                        break;
 296                }
 297                /* This function does all necessary parse...reuse it */
 298                ret = res_counter_memparse_write_strategy(buffer, &val);
 299                if (ret)
 300                        break;
 301                ret = res_counter_set_limit(&h_cg->hugepage[idx], val);
 302                break;
 303        default:
 304                ret = -EINVAL;
 305                break;
 306        }
 307        return ret;
 308}
 309
 310static int hugetlb_cgroup_reset(struct cgroup *cgroup, unsigned int event)
 311{
 312        int idx, name, ret = 0;
 313        struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_cgroup(cgroup);
 314
 315        idx = MEMFILE_IDX(event);
 316        name = MEMFILE_ATTR(event);
 317
 318        switch (name) {
 319        case RES_MAX_USAGE:
 320                res_counter_reset_max(&h_cg->hugepage[idx]);
 321                break;
 322        case RES_FAILCNT:
 323                res_counter_reset_failcnt(&h_cg->hugepage[idx]);
 324                break;
 325        default:
 326                ret = -EINVAL;
 327                break;
 328        }
 329        return ret;
 330}
 331
 332static char *mem_fmt(char *buf, int size, unsigned long hsize)
 333{
 334        if (hsize >= (1UL << 30))
 335                snprintf(buf, size, "%luGB", hsize >> 30);
 336        else if (hsize >= (1UL << 20))
 337                snprintf(buf, size, "%luMB", hsize >> 20);
 338        else
 339                snprintf(buf, size, "%luKB", hsize >> 10);
 340        return buf;
 341}
 342
 343int __init hugetlb_cgroup_file_init(int idx)
 344{
 345        char buf[32];
 346        struct cftype *cft;
 347        struct hstate *h = &hstates[idx];
 348
 349        /* format the size */
 350        mem_fmt(buf, 32, huge_page_size(h));
 351
 352        /* Add the limit file */
 353        cft = &h->cgroup_files[0];
 354        snprintf(cft->name, MAX_CFTYPE_NAME, "%s.limit_in_bytes", buf);
 355        cft->private = MEMFILE_PRIVATE(idx, RES_LIMIT);
 356        cft->read = hugetlb_cgroup_read;
 357        cft->write_string = hugetlb_cgroup_write;
 358
 359        /* Add the usage file */
 360        cft = &h->cgroup_files[1];
 361        snprintf(cft->name, MAX_CFTYPE_NAME, "%s.usage_in_bytes", buf);
 362        cft->private = MEMFILE_PRIVATE(idx, RES_USAGE);
 363        cft->read = hugetlb_cgroup_read;
 364
 365        /* Add the MAX usage file */
 366        cft = &h->cgroup_files[2];
 367        snprintf(cft->name, MAX_CFTYPE_NAME, "%s.max_usage_in_bytes", buf);
 368        cft->private = MEMFILE_PRIVATE(idx, RES_MAX_USAGE);
 369        cft->trigger = hugetlb_cgroup_reset;
 370        cft->read = hugetlb_cgroup_read;
 371
 372        /* Add the failcntfile */
 373        cft = &h->cgroup_files[3];
 374        snprintf(cft->name, MAX_CFTYPE_NAME, "%s.failcnt", buf);
 375        cft->private  = MEMFILE_PRIVATE(idx, RES_FAILCNT);
 376        cft->trigger  = hugetlb_cgroup_reset;
 377        cft->read = hugetlb_cgroup_read;
 378
 379        /* NULL terminate the last cft */
 380        cft = &h->cgroup_files[4];
 381        memset(cft, 0, sizeof(*cft));
 382
 383        WARN_ON(cgroup_add_cftypes(&hugetlb_subsys, h->cgroup_files));
 384
 385        return 0;
 386}
 387
 388/*
 389 * hugetlb_lock will make sure a parallel cgroup rmdir won't happen
 390 * when we migrate hugepages
 391 */
 392void hugetlb_cgroup_migrate(struct page *oldhpage, struct page *newhpage)
 393{
 394        struct hugetlb_cgroup *h_cg;
 395        struct hstate *h = page_hstate(oldhpage);
 396
 397        if (hugetlb_cgroup_disabled())
 398                return;
 399
 400        VM_BUG_ON(!PageHuge(oldhpage));
 401        spin_lock(&hugetlb_lock);
 402        h_cg = hugetlb_cgroup_from_page(oldhpage);
 403        set_hugetlb_cgroup(oldhpage, NULL);
 404
 405        /* move the h_cg details to new cgroup */
 406        set_hugetlb_cgroup(newhpage, h_cg);
 407        list_move(&newhpage->lru, &h->hugepage_activelist);
 408        spin_unlock(&hugetlb_lock);
 409        return;
 410}
 411
 412struct cgroup_subsys hugetlb_subsys = {
 413        .name = "hugetlb",
 414        .create     = hugetlb_cgroup_create,
 415        .pre_destroy = hugetlb_cgroup_pre_destroy,
 416        .destroy    = hugetlb_cgroup_destroy,
 417        .subsys_id  = hugetlb_subsys_id,
 418};
 419
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