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 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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