Commit d8ad3055 authored Jan 23, 2014 by Hugh Dickins Committed by Linus Torvalds Jan 23, 2014

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 <hughd@google.com>
Cc: Tejun Heo <tj@kernel.org>
Acked-by: Michal Hocko <mhocko@suse.cz>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: <stable@vger.kernel.org>	[3.12+]
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

parent d2ab70aa

mm/memcontrol.c

+2 −4

Original line number	Diff line number	Diff line
		@@ -1119,10 +1119,8 @@ static struct mem_cgroup __mem_cgroup_iter_next(struct mem_cgroup root,
		* 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;