On Sat 09-06-12 14:29:56, Aneesh Kumar K.V wrote:
> From: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
>
> This patchset add the charge and uncharge routines for hugetlb cgroup.
> This will be used in later patches when we allocate/free HugeTLB
> pages.
Please describe the locking rules.
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
> ---
> mm/hugetlb_cgroup.c | 87 +++++++++++++++++++++++++++++++++++++++++++++++++++
> 1 file changed, 87 insertions(+)
>
> diff --git a/mm/hugetlb_cgroup.c b/mm/hugetlb_cgroup.c
> index 20a32c5..48efd5a 100644
> --- a/mm/hugetlb_cgroup.c
> +++ b/mm/hugetlb_cgroup.c
> @@ -105,6 +105,93 @@ static int hugetlb_cgroup_pre_destroy(struct cgroup *cgroup)
> return -EBUSY;
> }
>
> +int hugetlb_cgroup_charge_page(int idx, unsigned long nr_pages,
> + struct hugetlb_cgroup **ptr)
Missing doc.
> +{
> + 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 (hstates[idx].order < 2)
> + goto done;
huge_page_order here? Not that important because we are using order in
the code directly at many places but easier for grep and maybe worth a
separate clean up patch.
> +again:
> + rcu_read_lock();
> + h_cg = hugetlb_cgroup_from_task(current);
> + if (!h_cg)
> + h_cg = root_h_cgroup;
> +
> + 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;
> +}
> +
> +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;
> +
> + spin_lock(&hugetlb_lock);
> + if (hugetlb_cgroup_from_page(page)) {
How can this happen? Is it possible that two CPUs are trying to charge
one page?
> + hugetlb_cgroup_uncharge_cgroup(idx, nr_pages, h_cg);
> + goto done;
> + }
> + set_hugetlb_cgroup(page, h_cg);
> +done:
> + spin_unlock(&hugetlb_lock);
> + return;
> +}
> +
> +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;
> +
> + spin_lock(&hugetlb_lock);
> + h_cg = hugetlb_cgroup_from_page(page);
> + if (unlikely(!h_cg)) {
> + spin_unlock(&hugetlb_lock);
> + return;
> + }
> + set_hugetlb_cgroup(page, NULL);
> + spin_unlock(&hugetlb_lock);
> +
> + 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)
> +{
Really worth a separate function to do the same tests again?
Will have a look at the follow up patches. It would be much easier if
the functions were used in the same patch...
> + unsigned long csize = nr_pages * PAGE_SIZE;
> +
> + if (hugetlb_cgroup_disabled() || !h_cg)
> + return;
> +
> + res_counter_uncharge(&h_cg->hugepage[idx], csize);
> + return;
> +}
> +
> struct cgroup_subsys hugetlb_subsys = {
> .name = "hugetlb",
> .create = hugetlb_cgroup_create,
> --
> 1.7.10
>
--
Michal Hocko
SUSE Labs
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9
Czech Republic
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