(2012/04/07 3:50), Aneesh Kumar K.V wrote:
> From: "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
>
> This add support for memcg removal with HugeTLB resource usage.
>
> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@xxxxxxxxxxxxxxxxxx>
Hmm
> +#ifdef CONFIG_MEM_RES_CTLR_HUGETLB
> +/*
> + * Force the memcg to empty the hugetlb resources by moving them to
> + * the parent cgroup. We can fail if the parent cgroup's limit prevented
> + * the charging. This should only happen if use_hierarchy is not set.
> + */
> +int hugetlb_force_memcg_empty(struct cgroup *cgroup)
> +{
> + struct hstate *h;
> + struct page *page;
> + int ret = 0, idx = 0;
> +
> + do {
> + if (cgroup_task_count(cgroup) || !list_empty(&cgroup->children))
> + goto out;
> + /*
> + * If the task doing the cgroup_rmdir got a signal
> + * we don't really need to loop till the hugetlb resource
> + * usage become zero.
> + */
> + if (signal_pending(current)) {
> + ret = -EINTR;
> + goto out;
> + }
> + for_each_hstate(h) {
> + spin_lock(&hugetlb_lock);
> + list_for_each_entry(page, &h->hugepage_activelist, lru) {
> + ret = mem_cgroup_move_hugetlb_parent(idx, cgroup, page);
> + if (ret) {
> + spin_unlock(&hugetlb_lock);
> + goto out;
> + }
> + }
> + spin_unlock(&hugetlb_lock);
> + idx++;
> + }
> + cond_resched();
> + } while (mem_cgroup_have_hugetlb_usage(cgroup));
> +out:
> + return ret;
> +}
> +#endif
> +
> /* Should be called on processing a hugepagesz=... option */
> void __init hugetlb_add_hstate(unsigned order)
> {
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 7d3330e..7b6e79a 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -3228,9 +3228,11 @@ static inline int mem_cgroup_move_swap_account(swp_entry_t entry,
> #endif
>
> #ifdef CONFIG_MEM_RES_CTLR_HUGETLB
> -static bool mem_cgroup_have_hugetlb_usage(struct mem_cgroup *memcg)
> +bool mem_cgroup_have_hugetlb_usage(struct cgroup *cgroup)
> {
> int idx;
> + struct mem_cgroup *memcg = mem_cgroup_from_cont(cgroup);
> +
> for (idx = 0; idx < hugetlb_max_hstate; idx++) {
> if ((res_counter_read_u64(&memcg->hugepage[idx], RES_USAGE)) > 0)
> return 1;
> @@ -3328,10 +3330,57 @@ void mem_cgroup_hugetlb_uncharge_memcg(int idx, unsigned long nr_pages,
> res_counter_uncharge(&memcg->hugepage[idx], csize);
> return;
> }
> -#else
> -static bool mem_cgroup_have_hugetlb_usage(struct mem_cgroup *memcg)
> +
> +int mem_cgroup_move_hugetlb_parent(int idx, struct cgroup *cgroup,
> + struct page *page)
> {
> - return 0;
> + struct page_cgroup *pc;
> + int csize, ret = 0;
> + struct res_counter *fail_res;
> + struct cgroup *pcgrp = cgroup->parent;
> + struct mem_cgroup *parent = mem_cgroup_from_cont(pcgrp);
> + struct mem_cgroup *memcg = mem_cgroup_from_cont(cgroup);
> +
> + if (!get_page_unless_zero(page))
> + goto out;
> +
> + pc = lookup_page_cgroup(page);
> + lock_page_cgroup(pc);
> + if (!PageCgroupUsed(pc) || pc->mem_cgroup != memcg)
> + goto err_out;
> +
> + csize = PAGE_SIZE << compound_order(page);
> + /*
> + * uncharge from child and charge the parent. If we have
> + * use_hierarchy set, we can never fail here. In-order to make
> + * sure we don't get -ENOMEM on parent charge, we first uncharge
> + * the child and then charge the parent.
> + */
> + if (parent->use_hierarchy) {
> + res_counter_uncharge(&memcg->hugepage[idx], csize);
> + if (!mem_cgroup_is_root(parent))
> + ret = res_counter_charge(&parent->hugepage[idx],
> + csize, &fail_res);
Ah, why is !mem_cgroup_is_root() checked ? no res_counter update for
root cgroup ?
I think it's better to have res_counter_move_parent()...to do ops in atomic.
(I'll post a patch for that for my purpose). OR, just ignore res->usage if
parent->use_hierarchy == 1.
uncharge->charge will have a race.
> + } else {
> + if (!mem_cgroup_is_root(parent)) {
> + ret = res_counter_charge(&parent->hugepage[idx],
> + csize, &fail_res);
> + if (ret) {
> + ret = -EBUSY;
> + goto err_out;
> + }
> + }
> + res_counter_uncharge(&memcg->hugepage[idx], csize);
> + }
Just a notice. Recently, Tejun changed failure of pre_destory() to show WARNING.
Then, I'd like to move the usage to the root cgroup if use_hierarchy=0.
Will it work for you ?
> + /*
> + * caller should have done css_get
> + */
Could you explain meaning of this comment ?
Thanks,
-Kame
> + pc->mem_cgroup = parent;
> +err_out:
> + unlock_page_cgroup(pc);
> + put_page(page);
> +out:
> + return ret;
> }
> #endif /* CONFIG_MEM_RES_CTLR_HUGETLB */
>
> @@ -3852,6 +3901,11 @@ static int mem_cgroup_force_empty(struct mem_cgroup *memcg, bool free_all)
> /* should free all ? */
> if (free_all)
> goto try_to_free;
> +
> + /* move the hugetlb charges */
> + ret = hugetlb_force_memcg_empty(cgrp);
> + if (ret)
> + goto out;
> move_account:
> do {
> ret = -EBUSY;
> @@ -5172,12 +5226,6 @@ free_out:
> static int mem_cgroup_pre_destroy(struct cgroup *cont)
> {
> struct mem_cgroup *memcg = mem_cgroup_from_cont(cont);
> - /*
> - * Don't allow memcg removal if we have HugeTLB resource
> - * usage.
> - */
> - if (mem_cgroup_have_hugetlb_usage(memcg))
> - return -EBUSY;
>
> return mem_cgroup_force_empty(memcg, false);
> }
--
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