hugetlb_cgroup.c

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/*
 *
 * Copyright IBM Corporation, 2012
 * Author Aneesh Kumar K.V <[email protected]>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of version 2.1 of the GNU Lesser General Public License
 * as published by the Free Software Foundation.
 *
 * This program is distributed in the hope that it would be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
 *
 */

#include <linux/cgroup.h>
#include <linux/slab.h>
#include <linux/hugetlb.h>
#include <linux/hugetlb_cgroup.h>

struct hugetlb_cgroup {
    struct cgroup_subsys_state css;
    /*
     * the counter to account for hugepages from hugetlb.
     */
    struct res_counter hugepage[HUGE_MAX_HSTATE];
};

#define MEMFILE_PRIVATE(x, val) (((x) << 16) | (val))
#define MEMFILE_IDX(val)    (((val) >> 16) & 0xffff)
#define MEMFILE_ATTR(val)   ((val) & 0xffff)

struct cgroup_subsys hugetlb_subsys __read_mostly;
static struct hugetlb_cgroup *root_h_cgroup __read_mostly;

static inline
struct hugetlb_cgroup *hugetlb_cgroup_from_css(struct cgroup_subsys_state *s)
{
    return container_of(s, struct hugetlb_cgroup, css);
}

static inline
struct hugetlb_cgroup *hugetlb_cgroup_from_cgroup(struct cgroup *cgroup)
{
    return hugetlb_cgroup_from_css(cgroup_subsys_state(cgroup,
                               hugetlb_subsys_id));
}

static inline
struct hugetlb_cgroup *hugetlb_cgroup_from_task(struct task_struct *task)
{
    return hugetlb_cgroup_from_css(task_subsys_state(task,
                             hugetlb_subsys_id));
}

static inline bool hugetlb_cgroup_is_root(struct hugetlb_cgroup *h_cg)
{
    return (h_cg == root_h_cgroup);
}

static inline struct hugetlb_cgroup *parent_hugetlb_cgroup(struct cgroup *cg)
{
    if (!cg->parent)
        return NULL;
    return hugetlb_cgroup_from_cgroup(cg->parent);
}

static inline bool hugetlb_cgroup_have_usage(struct cgroup *cg)
{
    int idx;
    struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_cgroup(cg);

    for (idx = 0; idx < hugetlb_max_hstate; idx++) {
        if ((res_counter_read_u64(&h_cg->hugepage[idx], RES_USAGE)) > 0)
            return true;
    }
    return false;
}

static struct cgroup_subsys_state *hugetlb_cgroup_create(struct cgroup *cgroup)
{
    int idx;
    struct cgroup *parent_cgroup;
    struct hugetlb_cgroup *h_cgroup, *parent_h_cgroup;

    h_cgroup = kzalloc(sizeof(*h_cgroup), GFP_KERNEL);
    if (!h_cgroup)
        return ERR_PTR(-ENOMEM);

    parent_cgroup = cgroup->parent;
    if (parent_cgroup) {
        parent_h_cgroup = hugetlb_cgroup_from_cgroup(parent_cgroup);
        for (idx = 0; idx < HUGE_MAX_HSTATE; idx++)
            res_counter_init(&h_cgroup->hugepage[idx],
                     &parent_h_cgroup->hugepage[idx]);
    } else {
        root_h_cgroup = h_cgroup;
        for (idx = 0; idx < HUGE_MAX_HSTATE; idx++)
            res_counter_init(&h_cgroup->hugepage[idx], NULL);
    }
    return &h_cgroup->css;
}

static void hugetlb_cgroup_destroy(struct cgroup *cgroup)
{
    struct hugetlb_cgroup *h_cgroup;

    h_cgroup = hugetlb_cgroup_from_cgroup(cgroup);
    kfree(h_cgroup);
}


/*
 * Should be called with hugetlb_lock held.
 * Since we are holding hugetlb_lock, pages cannot get moved from
 * active list or uncharged from the cgroup, So no need to get
 * page reference and test for page active here. This function
 * cannot fail.
 */
static void hugetlb_cgroup_move_parent(int idx, struct cgroup *cgroup,
                       struct page *page)
{
    int csize;
    struct res_counter *counter;
    struct res_counter *fail_res;
    struct hugetlb_cgroup *page_hcg;
    struct hugetlb_cgroup *h_cg   = hugetlb_cgroup_from_cgroup(cgroup);
    struct hugetlb_cgroup *parent = parent_hugetlb_cgroup(cgroup);

    page_hcg = hugetlb_cgroup_from_page(page);
    /*
     * We can have pages in active list without any cgroup
     * ie, hugepage with less than 3 pages. We can safely
     * ignore those pages.
     */
    if (!page_hcg || page_hcg != h_cg)
        goto out;

    csize = PAGE_SIZE << compound_order(page);
    if (!parent) {
        parent = root_h_cgroup;
        /* root has no limit */
        res_counter_charge_nofail(&parent->hugepage[idx],
                      csize, &fail_res);
    }
    counter = &h_cg->hugepage[idx];
    res_counter_uncharge_until(counter, counter->parent, csize);

    set_hugetlb_cgroup(page, parent);
out:
    return;
}

/*
 * Force the hugetlb cgroup to empty the hugetlb resources by moving them to
 * the parent cgroup.
 */
static int hugetlb_cgroup_pre_destroy(struct cgroup *cgroup)
{
    struct hstate *h;
    struct page *page;
    int ret = 0, idx = 0;

    do {
        if (cgroup_task_count(cgroup) ||
            !list_empty(&cgroup->children)) {
            ret = -EBUSY;
            goto out;
        }
        for_each_hstate(h) {
            spin_lock(&hugetlb_lock);
            list_for_each_entry(page, &h->hugepage_activelist, lru)
                hugetlb_cgroup_move_parent(idx, cgroup, page);

            spin_unlock(&hugetlb_lock);
            idx++;
        }
        cond_resched();
    } while (hugetlb_cgroup_have_usage(cgroup));
out:
    return ret;
}

int hugetlb_cgroup_charge_cgroup(int idx, unsigned long nr_pages,
                 struct hugetlb_cgroup **ptr)
{
    int ret = 0;
    struct res_counter *fail_res;
    struct hugetlb_cgroup *h_cg = NULL;
    unsigned long csize = nr_pages * PAGE_SIZE;

    if (hugetlb_cgroup_disabled())
        goto done;
    /*
     * We don't charge any cgroup if the compound page have less
     * than 3 pages.
     */
    if (huge_page_order(&hstates[idx]) < HUGETLB_CGROUP_MIN_ORDER)
        goto done;
again:
    rcu_read_lock();
    h_cg = hugetlb_cgroup_from_task(current);
    if (!css_tryget(&h_cg->css)) {
        rcu_read_unlock();
        goto again;
    }
    rcu_read_unlock();

    ret = res_counter_charge(&h_cg->hugepage[idx], csize, &fail_res);
    css_put(&h_cg->css);
done:
    *ptr = h_cg;
    return ret;
}

/* Should be called with hugetlb_lock held */
void hugetlb_cgroup_commit_charge(int idx, unsigned long nr_pages,
                  struct hugetlb_cgroup *h_cg,
                  struct page *page)
{
    if (hugetlb_cgroup_disabled() || !h_cg)
        return;

    set_hugetlb_cgroup(page, h_cg);
    return;
}

/*
 * Should be called with hugetlb_lock held
 */
void hugetlb_cgroup_uncharge_page(int idx, unsigned long nr_pages,
                  struct page *page)
{
    struct hugetlb_cgroup *h_cg;
    unsigned long csize = nr_pages * PAGE_SIZE;

    if (hugetlb_cgroup_disabled())
        return;
    VM_BUG_ON(!spin_is_locked(&hugetlb_lock));
    h_cg = hugetlb_cgroup_from_page(page);
    if (unlikely(!h_cg))
        return;
    set_hugetlb_cgroup(page, NULL);
    res_counter_uncharge(&h_cg->hugepage[idx], csize);
    return;
}

void hugetlb_cgroup_uncharge_cgroup(int idx, unsigned long nr_pages,
                    struct hugetlb_cgroup *h_cg)
{
    unsigned long csize = nr_pages * PAGE_SIZE;

    if (hugetlb_cgroup_disabled() || !h_cg)
        return;

    if (huge_page_order(&hstates[idx]) < HUGETLB_CGROUP_MIN_ORDER)
        return;

    res_counter_uncharge(&h_cg->hugepage[idx], csize);
    return;
}

static ssize_t hugetlb_cgroup_read(struct cgroup *cgroup, struct cftype *cft,
                   struct file *file, char __user *buf,
                   size_t nbytes, loff_t *ppos)
{
    u64 val;
    char str[64];
    int idx, name, len;
    struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_cgroup(cgroup);

    idx = MEMFILE_IDX(cft->private);
    name = MEMFILE_ATTR(cft->private);

    val = res_counter_read_u64(&h_cg->hugepage[idx], name);
    len = scnprintf(str, sizeof(str), "%llu\n", (unsigned long long)val);
    return simple_read_from_buffer(buf, nbytes, ppos, str, len);
}

static int hugetlb_cgroup_write(struct cgroup *cgroup, struct cftype *cft,
                const char *buffer)
{
    int idx, name, ret;
    unsigned long long val;
    struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_cgroup(cgroup);

    idx = MEMFILE_IDX(cft->private);
    name = MEMFILE_ATTR(cft->private);

    switch (name) {
    case RES_LIMIT:
        if (hugetlb_cgroup_is_root(h_cg)) {
            /* Can't set limit on root */
            ret = -EINVAL;
            break;
        }
        /* This function does all necessary parse...reuse it */
        ret = res_counter_memparse_write_strategy(buffer, &val);
        if (ret)
            break;
        ret = res_counter_set_limit(&h_cg->hugepage[idx], val);
        break;
    default:
        ret = -EINVAL;
        break;
    }
    return ret;
}

static int hugetlb_cgroup_reset(struct cgroup *cgroup, unsigned int event)
{
    int idx, name, ret = 0;
    struct hugetlb_cgroup *h_cg = hugetlb_cgroup_from_cgroup(cgroup);

    idx = MEMFILE_IDX(event);
    name = MEMFILE_ATTR(event);

    switch (name) {
    case RES_MAX_USAGE:
        res_counter_reset_max(&h_cg->hugepage[idx]);
        break;
    case RES_FAILCNT:
        res_counter_reset_failcnt(&h_cg->hugepage[idx]);
        break;
    default:
        ret = -EINVAL;
        break;
    }
    return ret;
}

static char *mem_fmt(char *buf, int size, unsigned long hsize)
{
    if (hsize >= (1UL << 30))
        snprintf(buf, size, "%luGB", hsize >> 30);
    else if (hsize >= (1UL << 20))
        snprintf(buf, size, "%luMB", hsize >> 20);
    else
        snprintf(buf, size, "%luKB", hsize >> 10);
    return buf;
}

int __init hugetlb_cgroup_file_init(int idx)
{
    char buf[32];
    struct cftype *cft;
    struct hstate *h = &hstates[idx];

    /* format the size */
    mem_fmt(buf, 32, huge_page_size(h));

    /* Add the limit file */
    cft = &h->cgroup_files[0];
    snprintf(cft->name, MAX_CFTYPE_NAME, "%s.limit_in_bytes", buf);
    cft->private = MEMFILE_PRIVATE(idx, RES_LIMIT);
    cft->read = hugetlb_cgroup_read;
    cft->write_string = hugetlb_cgroup_write;

    /* Add the usage file */
    cft = &h->cgroup_files[1];
    snprintf(cft->name, MAX_CFTYPE_NAME, "%s.usage_in_bytes", buf);
    cft->private = MEMFILE_PRIVATE(idx, RES_USAGE);
    cft->read = hugetlb_cgroup_read;

    /* Add the MAX usage file */
    cft = &h->cgroup_files[2];
    snprintf(cft->name, MAX_CFTYPE_NAME, "%s.max_usage_in_bytes", buf);
    cft->private = MEMFILE_PRIVATE(idx, RES_MAX_USAGE);
    cft->trigger = hugetlb_cgroup_reset;
    cft->read = hugetlb_cgroup_read;

    /* Add the failcntfile */
    cft = &h->cgroup_files[3];
    snprintf(cft->name, MAX_CFTYPE_NAME, "%s.failcnt", buf);
    cft->private  = MEMFILE_PRIVATE(idx, RES_FAILCNT);
    cft->trigger  = hugetlb_cgroup_reset;
    cft->read = hugetlb_cgroup_read;

    /* NULL terminate the last cft */
    cft = &h->cgroup_files[4];
    memset(cft, 0, sizeof(*cft));

    WARN_ON(cgroup_add_cftypes(&hugetlb_subsys, h->cgroup_files));

    return 0;
}

/*
 * hugetlb_lock will make sure a parallel cgroup rmdir won't happen
 * when we migrate hugepages
 */
void hugetlb_cgroup_migrate(struct page *oldhpage, struct page *newhpage)
{
    struct hugetlb_cgroup *h_cg;
    struct hstate *h = page_hstate(oldhpage);

    if (hugetlb_cgroup_disabled())
        return;

    VM_BUG_ON(!PageHuge(oldhpage));
    spin_lock(&hugetlb_lock);
    h_cg = hugetlb_cgroup_from_page(oldhpage);
    set_hugetlb_cgroup(oldhpage, NULL);

    /* move the h_cg details to new cgroup */
    set_hugetlb_cgroup(newhpage, h_cg);
    list_move(&newhpage->lru, &h->hugepage_activelist);
    spin_unlock(&hugetlb_lock);
    return;
}

struct cgroup_subsys hugetlb_subsys = {
    .name = "hugetlb",
    .create     = hugetlb_cgroup_create,
    .pre_destroy = hugetlb_cgroup_pre_destroy,
    .destroy    = hugetlb_cgroup_destroy,
    .subsys_id  = hugetlb_subsys_id,
};