[PATCH 2/8] mm: memcontrol: remove double kmem page_counter init

Johannes Weiner
2015-12-08T18:34:52Z

The kmem page_counter's limit is initialized to PAGE_COUNTER_MAX
inside mem_cgroup_css_online(). There is no need to repeat this
from memcg_propagate_kmem().

Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
---
mm/memcontrol.c | 24 ++++++++++--------------
1 file changed, 10 insertions(+), 14 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index eda8d43..02167db 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -2840,8 +2840,7 @@ static u64 mem_cgroup_read_u64(struct cgroup_subsys_state *css,
}

#ifdef CONFIG_MEMCG_KMEM
-static int memcg_activate_kmem(struct mem_cgroup *memcg,
- unsigned long nr_pages)
+static int memcg_activate_kmem(struct mem_cgroup *memcg)
{
int err = 0;
int memcg_id;
@@ -2876,13 +2875,6 @@ static int memcg_activate_kmem(struct mem_cgroup *memcg,
goto out;
}

- /*
- * We couldn't have accounted to this cgroup, because it hasn't got
- * activated yet, so this should succeed.
- */
- err = page_counter_limit(&memcg->kmem, nr_pages);
- VM_BUG_ON(err);
-
static_branch_inc(&memcg_kmem_enabled_key);
/*
* A memory cgroup is considered kmem-active as soon as it gets
@@ -2903,10 +2895,14 @@ static int memcg_update_kmem_limit(struct mem_cgroup *memcg,
int ret;

mutex_lock(&memcg_limit_mutex);
- if (!memcg_kmem_is_active(memcg))
- ret = memcg_activate_kmem(memcg, limit);
- else
- ret = page_counter_limit(&memcg->kmem, limit);
+ /* Top-level cgroup doesn't propagate from root */
+ if (!memcg_kmem_is_active(memcg)) {
+ ret = memcg_activate_kmem(memcg);
+ if (ret)
+ goto out;
+ }
+ ret = page_counter_limit(&memcg->kmem, limit);
+out:
mutex_unlock(&memcg_limit_mutex);
return ret;
}
@@ -2925,7 +2921,7 @@ static int memcg_propagate_kmem(struct mem_cgroup *memcg)
* after this point, because it has at least one child already.
*/
if (memcg_kmem_is_active(parent))
- ret = memcg_activate_kmem(memcg, PAGE_COUNTER_MAX);
+ ret = memcg_activate_kmem(memcg);
mutex_unlock(&memcg_limit_mutex);
return ret;
}
--
2.6.3