From 7e637de8591278f466558e1d75ed5f23cfd0b42b Mon Sep 17 00:00:00 2001 From: Glauber Costa Date: Wed, 20 Feb 2013 13:14:45 +1100 Subject: [PATCH] memcg: split part of memcg creation to css_online This patch is a preparatory work for later locking rework to get rid of big cgroup lock from memory controller code. The memory controller uses some tunables to adjust its operation. Those tunables are inherited from parent to children upon children intialization. For most of them, the value cannot be changed after the parent has a new children. cgroup core splits initialization in two phases: css_alloc and css_online. After css_alloc, the memory allocation and basic initialization are done. But the new group is not yet visible anywhere, not even for cgroup core code. It is only somewhere between css_alloc and css_online that it is inserted into the internal children lists. Copying tunable values in css_alloc will lead to inconsistent values: the children will copy the old parent values, that can change between the copy and the moment in which the groups is linked to any data structure that can indicate the presence of children. Signed-off-by: Glauber Costa Acked-by: Michal Hocko Cc: Tejun Heo Cc: Hiroyuki Kamezawa Cc: Johannes Weiner Signed-off-by: Andrew Morton --- mm/memcontrol.c | 62 +++++++++++++++++++++++++++++++------------------ 1 file changed, 40 insertions(+), 22 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 8e0988fee888..a9318963d5d5 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -6093,7 +6093,7 @@ err_cleanup: static struct cgroup_subsys_state * __ref mem_cgroup_css_alloc(struct cgroup *cont) { - struct mem_cgroup *memcg, *parent; + struct mem_cgroup *memcg; long error = -ENOMEM; int node; @@ -6108,7 +6108,7 @@ mem_cgroup_css_alloc(struct cgroup *cont) /* root ? */ if (cont->parent == NULL) { int cpu; - parent = NULL; + if (mem_cgroup_soft_limit_tree_init()) goto free_out; root_mem_cgroup = memcg; @@ -6117,13 +6117,43 @@ mem_cgroup_css_alloc(struct cgroup *cont) &per_cpu(memcg_stock, cpu); INIT_WORK(&stock->work, drain_local_stock); } - } else { - parent = mem_cgroup_from_cont(cont->parent); - memcg->use_hierarchy = parent->use_hierarchy; - memcg->oom_kill_disable = parent->oom_kill_disable; + + res_counter_init(&memcg->res, NULL); + res_counter_init(&memcg->memsw, NULL); + res_counter_init(&memcg->kmem, NULL); } - if (parent && parent->use_hierarchy) { + memcg->last_scanned_node = MAX_NUMNODES; + INIT_LIST_HEAD(&memcg->oom_notify); + atomic_set(&memcg->refcnt, 1); + memcg->move_charge_at_immigrate = 0; + mutex_init(&memcg->thresholds_lock); + spin_lock_init(&memcg->move_lock); + + return &memcg->css; + +free_out: + __mem_cgroup_free(memcg); + return ERR_PTR(error); +} + +static int +mem_cgroup_css_online(struct cgroup *cont) +{ + struct mem_cgroup *memcg, *parent; + int error = 0; + + if (!cont->parent) + return 0; + + memcg = mem_cgroup_from_cont(cont); + parent = mem_cgroup_from_cont(cont->parent); + + memcg->use_hierarchy = parent->use_hierarchy; + memcg->oom_kill_disable = parent->oom_kill_disable; + memcg->swappiness = mem_cgroup_swappiness(parent); + + if (parent->use_hierarchy) { res_counter_init(&memcg->res, &parent->res); res_counter_init(&memcg->memsw, &parent->memsw); res_counter_init(&memcg->kmem, &parent->kmem); @@ -6144,18 +6174,9 @@ mem_cgroup_css_alloc(struct cgroup *cont) * much sense so let cgroup subsystem know about this * unfortunate state in our controller. */ - if (parent && parent != root_mem_cgroup) + if (parent != root_mem_cgroup) mem_cgroup_subsys.broken_hierarchy = true; } - memcg->last_scanned_node = MAX_NUMNODES; - INIT_LIST_HEAD(&memcg->oom_notify); - - if (parent) - memcg->swappiness = mem_cgroup_swappiness(parent); - atomic_set(&memcg->refcnt, 1); - memcg->move_charge_at_immigrate = 0; - mutex_init(&memcg->thresholds_lock); - spin_lock_init(&memcg->move_lock); error = memcg_init_kmem(memcg, &mem_cgroup_subsys); if (error) { @@ -6165,12 +6186,8 @@ mem_cgroup_css_alloc(struct cgroup *cont) * call __mem_cgroup_free, so return directly */ mem_cgroup_put(memcg); - return ERR_PTR(error); } - return &memcg->css; -free_out: - __mem_cgroup_free(memcg); - return ERR_PTR(error); + return error; } static void mem_cgroup_css_offline(struct cgroup *cont) @@ -6780,6 +6797,7 @@ struct cgroup_subsys mem_cgroup_subsys = { .name = "memory", .subsys_id = mem_cgroup_subsys_id, .css_alloc = mem_cgroup_css_alloc, + .css_online = mem_cgroup_css_online, .css_offline = mem_cgroup_css_offline, .css_free = mem_cgroup_css_free, .can_attach = mem_cgroup_can_attach, -- 2.39.5