diff mbox series

memcg: Add comment to mem_cgroup_css_online()

Message ID 521f9e5f-c436-b388-fe83-4dc870bfb489@virtuozzo.com (mailing list archive)
State New, archived
Headers show
Series memcg: Add comment to mem_cgroup_css_online() | expand

Commit Message

Kirill Tkhai Aug. 2, 2018, 8:13 a.m. UTC 
Explain relationships between allocation and expanding.

Suggested-by: Vladimir Davydov <vdavydov.dev@gmail.com>
Signed-off-by: Kirill Tkhai <ktkhai@virtuozzo.com>
---
diff mbox series

Patch

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index d90993ef1d7d..34e5ff72ce87 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -4703,6 +4703,11 @@  static int mem_cgroup_css_online(struct cgroup_subsys_state *css)
 {
 	struct mem_cgroup *memcg = mem_cgroup_from_css(css);
 
+	/*
+	 * A memcg must be visible for memcg_expand_shrinker_maps()
+	 * by the time the maps are allocated. So, we allocate maps
+	 * here, when for_each_mem_cgroup() can't skip it.
+	 */
 	if (memcg_alloc_shrinker_maps(memcg)) {
 		mem_cgroup_id_remove(memcg);
 		return -ENOMEM;