This is a note to let you know that I've just added the patch titled
mm/memcg: iteration skip memcgs not yet fully initialized
to the 3.13-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
mm-memcg-iteration-skip-memcgs-not-yet-fully-initialized.patch
and it can be found in the queue-3.13 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From d8ad30559715ce97afb7d1a93a12fd90e8fff312 Mon Sep 17 00:00:00 2001
From: Hugh Dickins <hughd@xxxxxxxxxx>
Date: Thu, 23 Jan 2014 15:53:32 -0800
Subject: mm/memcg: iteration skip memcgs not yet fully initialized
From: Hugh Dickins <hughd@xxxxxxxxxx>
commit d8ad30559715ce97afb7d1a93a12fd90e8fff312 upstream.
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@xxxxxxxxxx>
Cc: Tejun Heo <tj@xxxxxxxxxx>
Acked-by: Michal Hocko <mhocko@xxxxxxx>
Cc: Johannes Weiner <hannes@xxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
mm/memcontrol.c | 6 ++----
1 file changed, 2 insertions(+), 4 deletions(-)
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1100,10 +1100,8 @@ 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;
Patches currently in stable-queue which might be from hughd@xxxxxxxxxx are
queue-3.13/memcg-fix-css-reference-leak-and-endless-loop-in-mem_cgroup_iter.patch
queue-3.13/memcg-fix-endless-loop-caused-by-mem_cgroup_iter.patch
queue-3.13/mm-memcg-iteration-skip-memcgs-not-yet-fully-initialized.patch
queue-3.13/mm-munlock-fix-potential-race-with-thp-page-split.patch
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