Root/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
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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