diff options
Diffstat (limited to 'mm/memcontrol.c')
| -rw-r--r-- | mm/memcontrol.c | 218 |
1 files changed, 1 insertions, 217 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 0e6484ea268d..f90e43c1499f 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1132,7 +1132,7 @@ struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root, if (css == &root->css) break; - if (css_tryget_online(css)) { + if (css_tryget(css)) { /* * Make sure the memcg is initialized: * mem_cgroup_css_online() orders the the @@ -3316,79 +3316,6 @@ out: return ret; } -/** - * mem_cgroup_move_parent - moves page to the parent group - * @page: the page to move - * @pc: page_cgroup of the page - * @child: page's cgroup - * - * move charges to its parent or the root cgroup if the group has no - * parent (aka use_hierarchy==0). - * Although this might fail (get_page_unless_zero, isolate_lru_page or - * mem_cgroup_move_account fails) the failure is always temporary and - * it signals a race with a page removal/uncharge or migration. In the - * first case the page is on the way out and it will vanish from the LRU - * on the next attempt and the call should be retried later. - * Isolation from the LRU fails only if page has been isolated from - * the LRU since we looked at it and that usually means either global - * reclaim or migration going on. The page will either get back to the - * LRU or vanish. - * Finaly mem_cgroup_move_account fails only if the page got uncharged - * (!PageCgroupUsed) or moved to a different group. The page will - * disappear in the next attempt. - */ -static int mem_cgroup_move_parent(struct page *page, - struct page_cgroup *pc, - struct mem_cgroup *child) -{ - struct mem_cgroup *parent; - unsigned int nr_pages; - unsigned long uninitialized_var(flags); - int ret; - - VM_BUG_ON(mem_cgroup_is_root(child)); - - ret = -EBUSY; - if (!get_page_unless_zero(page)) - goto out; - if (isolate_lru_page(page)) - goto put; - - nr_pages = hpage_nr_pages(page); - - parent = parent_mem_cgroup(child); - /* - * If no parent, move charges to root cgroup. - */ - if (!parent) - parent = root_mem_cgroup; - - if (nr_pages > 1) { - VM_BUG_ON_PAGE(!PageTransHuge(page), page); - flags = compound_lock_irqsave(page); - } - - ret = mem_cgroup_move_account(page, nr_pages, - pc, child, parent); - if (!ret) { - if (!mem_cgroup_is_root(parent)) - css_get_many(&parent->css, nr_pages); - /* Take charge off the local counters */ - page_counter_cancel(&child->memory, nr_pages); - if (do_swap_account) - page_counter_cancel(&child->memsw, nr_pages); - css_put_many(&child->css, nr_pages); - } - - if (nr_pages > 1) - compound_unlock_irqrestore(page, flags); - putback_lru_page(page); -put: - put_page(page); -out: - return ret; -} - #ifdef CONFIG_MEMCG_SWAP static void mem_cgroup_swap_statistics(struct mem_cgroup *memcg, bool charge) @@ -3682,105 +3609,6 @@ unsigned long mem_cgroup_soft_limit_reclaim(struct zone *zone, int order, return nr_reclaimed; } -/** - * mem_cgroup_force_empty_list - clears LRU of a group - * @memcg: group to clear - * @node: NUMA node - * @zid: zone id - * @lru: lru to to clear - * - * Traverse a specified page_cgroup list and try to drop them all. This doesn't - * reclaim the pages page themselves - pages are moved to the parent (or root) - * group. - */ -static void mem_cgroup_force_empty_list(struct mem_cgroup *memcg, - int node, int zid, enum lru_list lru) -{ - struct lruvec *lruvec; - unsigned long flags; - struct list_head *list; - struct page *busy; - struct zone *zone; - - zone = &NODE_DATA(node)->node_zones[zid]; - lruvec = mem_cgroup_zone_lruvec(zone, memcg); - list = &lruvec->lists[lru]; - - busy = NULL; - do { - struct page_cgroup *pc; - struct page *page; - - spin_lock_irqsave(&zone->lru_lock, flags); - if (list_empty(list)) { - spin_unlock_irqrestore(&zone->lru_lock, flags); - break; - } - page = list_entry(list->prev, struct page, lru); - if (busy == page) { - list_move(&page->lru, list); - busy = NULL; - spin_unlock_irqrestore(&zone->lru_lock, flags); - continue; - } - spin_unlock_irqrestore(&zone->lru_lock, flags); - - pc = lookup_page_cgroup(page); - - if (mem_cgroup_move_parent(page, pc, memcg)) { - /* found lock contention or "pc" is obsolete. */ - busy = page; - } else - busy = NULL; - cond_resched(); - } while (!list_empty(list)); -} - -/* - * make mem_cgroup's charge to be 0 if there is no task by moving - * all the charges and pages to the parent. - * This enables deleting this mem_cgroup. - * - * Caller is responsible for holding css reference on the memcg. - */ -static void mem_cgroup_reparent_charges(struct mem_cgroup *memcg) -{ - int node, zid; - - do { - /* 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_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. - */ - } while (page_counter_read(&memcg->memory) - - page_counter_read(&memcg->kmem) > 0); -} - /* * Test whether @memcg has children, dead or alive. Note that this * function doesn't care whether @memcg has use_hierarchy enabled and @@ -5323,7 +5151,6 @@ static void mem_cgroup_css_offline(struct cgroup_subsys_state *css) { struct mem_cgroup *memcg = mem_cgroup_from_css(css); struct mem_cgroup_event *event, *tmp; - struct cgroup_subsys_state *iter; /* * Unregister events and notify userspace. @@ -5337,13 +5164,6 @@ static void mem_cgroup_css_offline(struct cgroup_subsys_state *css) } spin_unlock(&memcg->event_list_lock); - /* - * This requires that offlining is serialized. Right now that is - * guaranteed because css_killed_work_fn() holds the cgroup_mutex. - */ - css_for_each_descendant_post(iter, css) - mem_cgroup_reparent_charges(mem_cgroup_from_css(iter)); - memcg_unregister_all_caches(memcg); vmpressure_cleanup(&memcg->vmpressure); } @@ -5351,42 +5171,6 @@ static void mem_cgroup_css_offline(struct cgroup_subsys_state *css) static void mem_cgroup_css_free(struct cgroup_subsys_state *css) { struct mem_cgroup *memcg = mem_cgroup_from_css(css); - /* - * XXX: css_offline() would be where we should reparent all - * memory to prepare the cgroup for destruction. However, - * memcg does not do css_tryget_online() and page_counter charging - * under the same RCU lock region, which means that charging - * could race with offlining. Offlining only happens to - * cgroups with no tasks in them but charges can show up - * without any tasks from the swapin path when the target - * memcg is looked up from the swapout record and not from the - * current task as it usually is. A race like this can leak - * charges and put pages with stale cgroup pointers into - * circulation: - * - * #0 #1 - * lookup_swap_cgroup_id() - * rcu_read_lock() - * mem_cgroup_lookup() - * css_tryget_online() - * rcu_read_unlock() - * disable css_tryget_online() - * call_rcu() - * offline_css() - * reparent_charges() - * page_counter_try_charge() - * css_put() - * css_free() - * pc->mem_cgroup = dead memcg - * add page to lru - * - * The bulk of the charges are still moved in offline_css() to - * avoid pinning a lot of pages in case a long-term reference - * like a swapout record is deferring the css_free() to long - * after offlining. But this makes sure we catch any charges - * made after offlining: - */ - mem_cgroup_reparent_charges(memcg); memcg_destroy_kmem(memcg); __mem_cgroup_free(memcg); |