From: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Subject: mm: memcontrol: reword obsolete comment of mem_cgroup_unmark_under_oom()
Since commit 79dfdaccd1d5 ("memcg: make oom_lock 0 and 1 based rather than
counter"), the mem_cgroup_unmark_under_oom() is added and the comment of
the mem_cgroup_oom_unlock() is moved here. But this comment make no sense
here because mem_cgroup_oom_lock() does not operate on under_oom field.
So we reword the comment as this would be helpful. [Thanks Michal Hocko
for rewording this comment.]
Link: https://lkml.kernel.org/r/20200930095336.21323-1-linmiaohe@xxxxxxxxxx
Signed-off-by: Miaohe Lin <linmiaohe@xxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Cc: Vladimir Davydov <vdavydov.dev@xxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
mm/memcontrol.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/mm/memcontrol.c~mm-memcontrol-reword-obsolete-comment-of-mem_cgroup_unmark_under_oom
+++ a/mm/memcontrol.c
@@ -1826,8 +1826,8 @@ static void mem_cgroup_unmark_under_oom(
struct mem_cgroup *iter;
/*
- * When a new child is created while the hierarchy is under oom,
- * mem_cgroup_oom_lock() may not be called. Watch for underflow.
+ * Be careful about under_oom underflows becase a child memcg
+ * could have been added after mem_cgroup_mark_under_oom.
*/
spin_lock(&memcg_oom_lock);
for_each_mem_cgroup_tree(iter, memcg)
_
