As charges now pin the css explicitely, there is no more need for kmemcg to acquire a proxy reference for outstanding pages during offlining, or maintain state to identify such "dead" groups.
Signed-off-by: Johannes Weiner <[email protected]> --- mm/memcontrol.c | 74 +-------------------------------------------------------- 1 file changed, 1 insertion(+), 73 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index b832c87ec43b..019a44ac25d6 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -471,7 +471,6 @@ struct mem_cgroup { /* internal only representation about the status of kmem accounting. */ enum { KMEM_ACCOUNTED_ACTIVE, /* accounted by this cgroup itself */ - KMEM_ACCOUNTED_DEAD, /* dead memcg with pending kmem charges */ }; #ifdef CONFIG_MEMCG_KMEM @@ -485,22 +484,6 @@ static bool memcg_kmem_is_active(struct mem_cgroup *memcg) return test_bit(KMEM_ACCOUNTED_ACTIVE, &memcg->kmem_account_flags); } -static void memcg_kmem_mark_dead(struct mem_cgroup *memcg) -{ - /* - * Our caller must use css_get() first, because memcg_uncharge_kmem() - * will call css_put() if it sees the memcg is dead. - */ - smp_wmb(); - if (test_bit(KMEM_ACCOUNTED_ACTIVE, &memcg->kmem_account_flags)) - set_bit(KMEM_ACCOUNTED_DEAD, &memcg->kmem_account_flags); -} - -static bool memcg_kmem_test_and_clear_dead(struct mem_cgroup *memcg) -{ - return test_and_clear_bit(KMEM_ACCOUNTED_DEAD, - &memcg->kmem_account_flags); -} #endif /* Stuffs for move charges at task migration. */ @@ -2807,22 +2790,7 @@ static void memcg_uncharge_kmem(struct mem_cgroup *memcg, if (do_swap_account) page_counter_uncharge(&memcg->memsw, nr_pages); - /* Not down to 0 */ - if (page_counter_uncharge(&memcg->kmem, nr_pages)) { - css_put_many(&memcg->css, nr_pages); - return; - } - - /* - * Releases a reference taken in kmem_cgroup_css_offline in case - * this last uncharge is racing with the offlining code or it is - * outliving the memcg existence. - * - * The memory barrier imposed by test&clear is paired with the - * explicit one in memcg_kmem_mark_dead(). - */ - if (memcg_kmem_test_and_clear_dead(memcg)) - css_put(&memcg->css); + page_counter_uncharge(&memcg->kmem, nr_pages); css_put_many(&memcg->css, nr_pages); } @@ -4805,40 +4773,6 @@ static void memcg_destroy_kmem(struct mem_cgroup *memcg) { mem_cgroup_sockets_destroy(memcg); } - -static void kmem_cgroup_css_offline(struct mem_cgroup *memcg) -{ - if (!memcg_kmem_is_active(memcg)) - return; - - /* - * kmem charges can outlive the cgroup. In the case of slab - * pages, for instance, a page contain objects from various - * processes. As we prevent from taking a reference for every - * such allocation we have to be careful when doing uncharge - * (see memcg_uncharge_kmem) and here during offlining. - * - * The idea is that that only the _last_ uncharge which sees - * the dead memcg will drop the last reference. An additional - * reference is taken here before the group is marked dead - * which is then paired with css_put during uncharge resp. here. - * - * Although this might sound strange as this path is called from - * css_offline() when the referencemight have dropped down to 0 and - * shouldn't be incremented anymore (css_tryget_online() would - * fail) we do not have other options because of the kmem - * allocations lifetime. - */ - css_get(&memcg->css); - - memcg_kmem_mark_dead(memcg); - - if (atomic_long_read(&memcg->kmem.count)) - return; - - if (memcg_kmem_test_and_clear_dead(memcg)) - css_put(&memcg->css); -} #else static int memcg_init_kmem(struct mem_cgroup *memcg, struct cgroup_subsys *ss) { @@ -4848,10 +4782,6 @@ static int memcg_init_kmem(struct mem_cgroup *memcg, struct cgroup_subsys *ss) static void memcg_destroy_kmem(struct mem_cgroup *memcg) { } - -static void kmem_cgroup_css_offline(struct mem_cgroup *memcg) -{ -} #endif /* @@ -5443,8 +5373,6 @@ static void mem_cgroup_css_offline(struct cgroup_subsys_state *css) } spin_unlock(&memcg->event_list_lock); - kmem_cgroup_css_offline(memcg); - /* * This requires that offlining is serialized. Right now that is * guaranteed because css_killed_work_fn() holds the cgroup_mutex. -- 2.1.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
