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author | Glauber Costa <glommer@parallels.com> | 2013-02-22 16:34:56 -0800 |
---|---|---|
committer | Linus Torvalds <torvalds@linux-foundation.org> | 2013-02-23 17:50:18 -0800 |
commit | 692e89abd154b04d212dce0c18a449bda15aac04 (patch) | |
tree | 91073f62049a9ffe49686cd10d4fd5cb09b26ac7 /mm/memcontrol.c | |
parent | 0999821b1d08f69e3879eb8fa0d28c4aba82ab5e (diff) | |
download | linux-692e89abd154b04d212dce0c18a449bda15aac04.tar.gz linux-692e89abd154b04d212dce0c18a449bda15aac04.tar.bz2 linux-692e89abd154b04d212dce0c18a449bda15aac04.zip |
memcg: increment static branch right after limit set
We were deferring the kmemcg static branch increment to a later time,
due to a nasty dependency between the cpu_hotplug lock, taken by the
jump label update, and the cgroup_lock.
Now we no longer take the cgroup lock, and we can save ourselves the
trouble.
Signed-off-by: Glauber Costa <glommer@parallels.com>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Tejun Heo <tj@kernel.org>
Cc: Hiroyuki Kamezawa <kamezawa.hiroyuki@gmail.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/memcontrol.c')
-rw-r--r-- | mm/memcontrol.c | 31 |
1 files changed, 7 insertions, 24 deletions
diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 46cdaef78b01..f4f41c36e703 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -4974,8 +4974,6 @@ static int memcg_update_kmem_limit(struct cgroup *cont, u64 val) { int ret = -EINVAL; #ifdef CONFIG_MEMCG_KMEM - bool must_inc_static_branch = false; - struct mem_cgroup *memcg = mem_cgroup_from_cont(cont); /* * For simplicity, we won't allow this to be disabled. It also can't @@ -5004,7 +5002,13 @@ static int memcg_update_kmem_limit(struct cgroup *cont, u64 val) res_counter_set_limit(&memcg->kmem, RESOURCE_MAX); goto out; } - must_inc_static_branch = true; + static_key_slow_inc(&memcg_kmem_enabled_key); + /* + * setting the active bit after the inc will guarantee no one + * starts accounting before all call sites are patched + */ + memcg_kmem_set_active(memcg); + /* * kmem charges can outlive the cgroup. In the case of slab * pages, for instance, a page contain objects from various @@ -5017,27 +5021,6 @@ static int memcg_update_kmem_limit(struct cgroup *cont, u64 val) out: mutex_unlock(&set_limit_mutex); mutex_unlock(&memcg_create_mutex); - - /* - * We are by now familiar with the fact that we can't inc the static - * branch inside cgroup_lock. See disarm functions for details. A - * worker here is overkill, but also wrong: After the limit is set, we - * must start accounting right away. Since this operation can't fail, - * we can safely defer it to here - no rollback will be needed. - * - * The boolean used to control this is also safe, because - * KMEM_ACCOUNTED_ACTIVATED guarantees that only one process will be - * able to set it to true; - */ - if (must_inc_static_branch) { - static_key_slow_inc(&memcg_kmem_enabled_key); - /* - * setting the active bit after the inc will guarantee no one - * starts accounting before all call sites are patched - */ - memcg_kmem_set_active(memcg); - } - #endif return ret; } |