From d8ad30559715ce97afb7d1a93a12fd90e8fff312 Mon Sep 17 00:00:00 2001 From: Hugh Dickins Date: Thu, 23 Jan 2014 15:53:32 -0800 Subject: [PATCH] mm/memcg: iteration skip memcgs not yet fully initialized It is surprising that the mem_cgroup iterator can return memcgs which have not yet been fully initialized. By accident (or trial and error?) this appears not to present an actual problem; but it may be better to prevent such surprises, by skipping memcgs not yet online. Signed-off-by: Hugh Dickins Cc: Tejun Heo Acked-by: Michal Hocko Cc: Johannes Weiner Cc: [3.12+] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/memcontrol.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index aa66cc4c9e79..9537e1389ee6 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1119,10 +1119,8 @@ skip_node: * protected by css_get and the tree walk is rcu safe. */ if (next_css) { - struct mem_cgroup *mem = mem_cgroup_from_css(next_css); - - if (css_tryget(&mem->css)) - return mem; + if ((next_css->flags & CSS_ONLINE) && css_tryget(next_css)) + return mem_cgroup_from_css(next_css); else { prev_css = next_css; goto skip_node; -- 2.20.1