Subject: + memcg-dont-need-to-get-a-reference-to-the-parent.patch added to -mm tree To: lizefan@xxxxxxxxxx,glommer@xxxxxxxxxx,hannes@xxxxxxxxxxx,hughd@xxxxxxxxxx,kamezawa.hiroyu@xxxxxxxxxxxxxx,mhocko@xxxxxxx,tj@xxxxxxxxxx From: akpm@xxxxxxxxxxxxxxxxxxxx Date: Fri, 28 Jun 2013 16:00:32 -0700 The patch titled Subject: memcg: don't need to get a reference to the parent has been added to the -mm tree. Its filename is memcg-dont-need-to-get-a-reference-to-the-parent.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: Li Zefan <lizefan@xxxxxxxxxx> Subject: memcg: don't need to get a reference to the parent The cgroup core guarantees it's always safe to access the parent. Signed-off-by: Li Zefan <lizefan@xxxxxxxxxx> Acked-by: Michal Hocko <mhocko@xxxxxxx> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx> Cc: Hugh Dickins <hughd@xxxxxxxxxx> Cc: Tejun Heo <tj@xxxxxxxxxx> Cc: Glauber Costa <glommer@xxxxxxxxxx> Cc: Johannes Weiner <hannes@xxxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- mm/memcontrol.c | 19 +++---------------- 1 file changed, 3 insertions(+), 16 deletions(-) diff -puN mm/memcontrol.c~memcg-dont-need-to-get-a-reference-to-the-parent mm/memcontrol.c --- a/mm/memcontrol.c~memcg-dont-need-to-get-a-reference-to-the-parent +++ a/mm/memcontrol.c @@ -503,7 +503,6 @@ enum res_type { */ static DEFINE_MUTEX(memcg_create_mutex); -static void mem_cgroup_get(struct mem_cgroup *memcg); static void mem_cgroup_put(struct mem_cgroup *memcg); static inline @@ -6230,19 +6229,10 @@ static void free_rcu(struct rcu_head *rc schedule_work(&memcg->work_freeing); } -static void mem_cgroup_get(struct mem_cgroup *memcg) -{ - atomic_inc(&memcg->refcnt); -} - static void __mem_cgroup_put(struct mem_cgroup *memcg, int count) { - if (atomic_sub_and_test(count, &memcg->refcnt)) { - struct mem_cgroup *parent = parent_mem_cgroup(memcg); + if (atomic_sub_and_test(count, &memcg->refcnt)) call_rcu(&memcg->rcu_freeing, free_rcu); - if (parent) - mem_cgroup_put(parent); - } } static void mem_cgroup_put(struct mem_cgroup *memcg) @@ -6345,12 +6335,9 @@ mem_cgroup_css_online(struct cgroup *con res_counter_init(&memcg->kmem, &parent->kmem); /* - * We increment refcnt of the parent to ensure that we can - * safely access it on res_counter_charge/uncharge. - * This refcnt will be decremented when freeing this - * mem_cgroup(see mem_cgroup_put). + * No need to take a reference to the parent because cgroup + * core guarantees its existence. */ - mem_cgroup_get(parent); } else { res_counter_init(&memcg->res, NULL); res_counter_init(&memcg->memsw, NULL); _ Patches currently in -mm which might be from lizefan@xxxxxxxxxx are origin.patch linux-next.patch memcg-update-todo-list-in-documentation.patch revert-memcg-avoid-dangling-reference-count-in-creation-failure.patch memcg-kmem-fix-reference-count-handling-on-the-error-path.patch memcg-use-css_get-in-sock_update_memcg.patch memcg-dont-use-mem_cgroup_get-when-creating-a-kmemcg-cache.patch memcg-use-css_get-put-when-charging-uncharging-kmem.patch memcg-use-css_get-put-when-charging-uncharging-kmem-fix.patch memcg-use-css_get-put-for-swap-memcg.patch memcg-dont-need-to-get-a-reference-to-the-parent.patch memcg-kill-memcg-refcnt.patch memcg-dont-need-to-free-memcg-via-rcu-or-workqueue.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html