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 struct cgroup_subsys hugetlb_subsys __read_mostly;
  30 static struct hugetlb_cgroup *root_h_cgroup __read_mostly;
  31
  32 static inline
  33 struct hugetlb_cgroup *hugetlb_cgroup_from_css(struct cgroup_subsys_state *s)
  34 {
  35         return container_of(s, struct hugetlb_cgroup, css);
  36 }
  37
  38 static inline
  39 struct hugetlb_cgroup *hugetlb_cgroup_from_cgroup(struct cgroup *cgroup)
  40 {
  41         return hugetlb_cgroup_from_css(cgroup_subsys_state(cgroup,
  42                                                            hugetlb_subsys_id));
  43 }
  44
  45 static inline
  46 struct hugetlb_cgroup *hugetlb_cgroup_from_task(struct task_struct *task)
  47 {
  48         return hugetlb_cgroup_from_css(task_subsys_state(task,
  49                                                          hugetlb_subsys_id));
  50 }
  51
  52 static inline bool hugetlb_cgroup_is_root(struct hugetlb_cgroup *h_cg)
  53 {
  54         return (h_cg == root_h_cgroup);
  55 }
  56
  57 static inline struct hugetlb_cgroup *parent_hugetlb_cgroup(struct cgroup *cg)
  58 {
  59         if (!cg->parent)
  60                 return NULL;
  61         return hugetlb_cgroup_from_cgroup(cg->parent);
  62 }
  63
  64 static inline bool hugetlb_cgroup_have_usage(struct cgroup *cg)
  65 {
  66         int idx;
  67         struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_cgroup(cg);
  68
  69         for (idx = 0; idx < hugetlb_max_hstate; idx++) {
  70                 if ((res_counter_read_u64(&h_cg->hugepage[idx], RES_USAGE)) > 0)
  71                         return true;
  72         }
  73         return false;
  74 }
  75
  76 static struct cgroup_subsys_state *hugetlb_cgroup_create(struct cgroup *cgroup)
  77 {
  78         int idx;
  79         struct cgroup *parent_cgroup;
  80         struct hugetlb_cgroup *h_cgroup, *parent_h_cgroup;
  81
  82         h_cgroup = kzalloc(sizeof(*h_cgroup), GFP_KERNEL);
  83         if (!h_cgroup)
  84                 return ERR_PTR(-ENOMEM);
  85
  86         parent_cgroup = cgroup->parent;
  87         if (parent_cgroup) {
  88                 parent_h_cgroup = hugetlb_cgroup_from_cgroup(parent_cgroup);
  89                 for (idx = 0; idx < HUGE_MAX_HSTATE; idx++)
  90                         res_counter_init(&h_cgroup->hugepage[idx],
  91                                          &parent_h_cgroup->hugepage[idx]);
  92         } else {
  93                 root_h_cgroup = h_cgroup;
  94                 for (idx = 0; idx < HUGE_MAX_HSTATE; idx++)
  95                         res_counter_init(&h_cgroup->hugepage[idx], NULL);
  96         }
  97         return &h_cgroup->css;
  98 }
  99
 100 static void hugetlb_cgroup_destroy(struct cgroup *cgroup)
 101 {
 102         struct hugetlb_cgroup *h_cgroup;
 103
 104         h_cgroup = hugetlb_cgroup_from_cgroup(cgroup);
 105         kfree(h_cgroup);
 106 }
 107
 108
 109 /*
 110  * Should be called with hugetlb_lock held.
 111  * Since we are holding hugetlb_lock, pages cannot get moved from
 112  * active list or uncharged from the cgroup, So no need to get
 113  * page reference and test for page active here. This function
 114  * cannot fail.
 115  */
 116 static void hugetlb_cgroup_move_parent(int idx, struct cgroup *cgroup,
 117                                        struct page *page)
 118 {
 119         int csize;
 120         struct res_counter *counter;
 121         struct res_counter *fail_res;
 122         struct hugetlb_cgroup *page_hcg;
 123         struct hugetlb_cgroup *h_cg   = hugetlb_cgroup_from_cgroup(cgroup);
 124         struct hugetlb_cgroup *parent = parent_hugetlb_cgroup(cgroup);
 125
 126         page_hcg = hugetlb_cgroup_from_page(page);
 127         /*
 128          * We can have pages in active list without any cgroup
 129          * ie, hugepage with less than 3 pages. We can safely
 130          * ignore those pages.
 131          */
 132         if (!page_hcg || page_hcg != h_cg)
 133                 goto out;
 134
 135         csize = PAGE_SIZE << compound_order(page);
 136         if (!parent) {
 137                 parent = root_h_cgroup;
 138                 /* root has no limit */
 139                 res_counter_charge_nofail(&parent->hugepage[idx],
 140                                           csize, &fail_res);
 141         }
 142         counter = &h_cg->hugepage[idx];
 143         res_counter_uncharge_until(counter, counter->parent, csize);
 144
 145         set_hugetlb_cgroup(page, parent);
 146 out:
 147         return;
 148 }
 149
 150 /*
 151  * Force the hugetlb cgroup to empty the hugetlb resources by moving them to
 152  * the parent cgroup.
 153  */
 154 static int hugetlb_cgroup_pre_destroy(struct cgroup *cgroup)
 155 {
 156         struct hstate *h;
 157         struct page *page;
 158         int ret = 0, idx = 0;
 159
 160         do {
 161                 if (cgroup_task_count(cgroup) ||
 162                     !list_empty(&cgroup->children)) {
 163                         ret = -EBUSY;
 164                         goto out;
 165                 }
 166                 for_each_hstate(h) {
 167                         spin_lock(&hugetlb_lock);
 168                         list_for_each_entry(page, &h->hugepage_activelist, lru)
 169                                 hugetlb_cgroup_move_parent(idx, cgroup, page);
 170
 171                         spin_unlock(&hugetlb_lock);
 172                         idx++;
 173                 }
 174                 cond_resched();
 175         } while (hugetlb_cgroup_have_usage(cgroup));
 176 out:
 177         return ret;
 178 }
 179
 180 int hugetlb_cgroup_charge_cgroup(int idx, unsigned long nr_pages,
 181                                  struct hugetlb_cgroup **ptr)
 182 {
 183         int ret = 0;
 184         struct res_counter *fail_res;
 185         struct hugetlb_cgroup *h_cg = NULL;
 186         unsigned long csize = nr_pages * PAGE_SIZE;
 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;
 196 again:
 197         rcu_read_lock();
 198         h_cg = hugetlb_cgroup_from_task(current);
 199         if (!css_tryget(&h_cg->css)) {
 200                 rcu_read_unlock();
 201                 goto again;
 202         }
 203         rcu_read_unlock();
 204
 205         ret = res_counter_charge(&h_cg->hugepage[idx], csize, &fail_res);
 206         css_put(&h_cg->css);
 207 done:
 208         *ptr = h_cg;
 209         return ret;
 210 }
 211
 212 void hugetlb_cgroup_commit_charge(int idx, unsigned long nr_pages,
 213                                   struct hugetlb_cgroup *h_cg,
 214                                   struct page *page)
 215 {
 216         if (hugetlb_cgroup_disabled() || !h_cg)
 217                 return;
 218
 219         spin_lock(&hugetlb_lock);
 220         set_hugetlb_cgroup(page, h_cg);
 221         spin_unlock(&hugetlb_lock);
 222         return;
 223 }
 224
 225 /*
 226  * Should be called with hugetlb_lock held
 227  */
 228 void hugetlb_cgroup_uncharge_page(int idx, unsigned long nr_pages,
 229                                   struct page *page)
 230 {
 231         struct hugetlb_cgroup *h_cg;
 232         unsigned long csize = nr_pages * PAGE_SIZE;
 233
 234         if (hugetlb_cgroup_disabled())
 235                 return;
 236         VM_BUG_ON(!spin_is_locked(&hugetlb_lock));
 237         h_cg = hugetlb_cgroup_from_page(page);
 238         if (unlikely(!h_cg))
 239                 return;
 240         set_hugetlb_cgroup(page, NULL);
 241         res_counter_uncharge(&h_cg->hugepage[idx], csize);
 242         return;
 243 }
 244
 245 void hugetlb_cgroup_uncharge_cgroup(int idx, unsigned long nr_pages,
 246                                     struct hugetlb_cgroup *h_cg)
 247 {
 248         unsigned long csize = nr_pages * PAGE_SIZE;
 249
 250         if (hugetlb_cgroup_disabled() || !h_cg)
 251                 return;
 252
 253         if (huge_page_order(&hstates[idx]) < HUGETLB_CGROUP_MIN_ORDER)
 254                 return;
 255
 256         res_counter_uncharge(&h_cg->hugepage[idx], csize);
 257         return;
 258 }
 259
 260 struct cgroup_subsys hugetlb_subsys = {
 261         .name = "hugetlb",
 262         .create     = hugetlb_cgroup_create,
 263         .pre_destroy = hugetlb_cgroup_pre_destroy,
 264         .destroy    = hugetlb_cgroup_destroy,
 265         .subsys_id  = hugetlb_subsys_id,
 266 };