Messages in this thread | | | Date | Thu, 1 Nov 2012 17:05:39 -0700 | From | Andrew Morton <> | Subject | Re: [PATCH v6 11/29] memcg: allow a memcg with kmem charges to be destructed. |
| |
On Thu, 1 Nov 2012 16:07:27 +0400 Glauber Costa <glommer@parallels.com> wrote:
> Because the ultimate goal of the kmem tracking in memcg is to track slab > pages as well, we can't guarantee that we'll always be able to point a > page to a particular process, and migrate the charges along with it - > since in the common case, a page will contain data belonging to multiple > processes. > > Because of that, when we destroy a memcg, we only make sure the > destruction will succeed by discounting the kmem charges from the user > charges when we try to empty the cgroup.
There was a significant conflict with the sched/numa changes in linux-next, which I resolved as below. Please check it.
static int mem_cgroup_reparent_charges(struct mem_cgroup *memcg) { struct cgroup *cgrp = memcg->css.cgroup; int node, zid; u64 usage;
do { if (cgroup_task_count(cgrp) || !list_empty(&cgrp->children)) return -EBUSY; /* This is for making all *used* pages to be on LRU. */ lru_add_drain_all(); drain_all_stock_sync(memcg); mem_cgroup_start_move(memcg); for_each_node_state(node, N_HIGH_MEMORY) { for (zid = 0; zid < MAX_NR_ZONES; zid++) { enum lru_list lru; for_each_lru(lru) { mem_cgroup_force_empty_list(memcg, node, zid, lru); } } } mem_cgroup_end_move(memcg); memcg_oom_recover(memcg); cond_resched();
/* * Kernel memory may not necessarily be trackable to a specific * process. So they are not migrated, and therefore we can't * expect their value to drop to 0 here. * Having res filled up with kmem only is enough. * * This is a safety check because mem_cgroup_force_empty_list * could have raced with mem_cgroup_replace_page_cache callers * so the lru seemed empty but the page could have been added * right after the check. RES_USAGE should be safe as we always * charge before adding to the LRU. */ usage = res_counter_read_u64(&memcg->res, RES_USAGE) - res_counter_read_u64(&memcg->kmem, RES_USAGE); } while (usage > 0);
return 0; }
| |