[087/181] mm: memcontrol: reword obsolete comment of mem_cgroup_unmark_under_oom()

Commit Message

Andrew Morton Oct. 13, 2020, 11:53 p.m. UTC

From: Miaohe Lin <[e-mail]>
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/[e-mail]
Signed-off-by: Miaohe Lin <[e-mail]>
Acked-by: Michal Hocko <[e-mail]>
Cc: Johannes Weiner <[e-mail]>
Cc: Vladimir Davydov <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 mm/memcontrol.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

Patch

--- 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)