This is a note to let you know that I've just added the patch titled
cgroup: notify_on_release may not be triggered in some cases
to the 3.0-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:
cgroup-notify_on_release-may-not-be-triggered-in-some-cases.patch
and it can be found in the queue-3.0 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <[email protected]> know about it.
>From 1f5320d5972aa50d3e8d2b227b636b370e608359 Mon Sep 17 00:00:00 2001
From: Daisuke Nishimura <[email protected]>
Date: Thu, 4 Oct 2012 16:37:16 +0900
Subject: cgroup: notify_on_release may not be triggered in some cases
From: Daisuke Nishimura <[email protected]>
commit 1f5320d5972aa50d3e8d2b227b636b370e608359 upstream.
notify_on_release must be triggered when the last process in a cgroup is
move to another. But if the first(and only) process in a cgroup is moved to
another, notify_on_release is not triggered.
# mkdir /cgroup/cpu/SRC
# mkdir /cgroup/cpu/DST
#
# echo 1 >/cgroup/cpu/SRC/notify_on_release
# echo 1 >/cgroup/cpu/DST/notify_on_release
#
# sleep 300 &
[1] 8629
#
# echo 8629 >/cgroup/cpu/SRC/tasks
# echo 8629 >/cgroup/cpu/DST/tasks
-> notify_on_release for /SRC must be triggered at this point,
but it isn't.
This is because put_css_set() is called before setting CGRP_RELEASABLE
in cgroup_task_migrate(), and is a regression introduce by the
commit:74a1166d(cgroups: make procs file writable), which was merged
into v3.0.
Acked-by: Li Zefan <[email protected]>
Cc: Ben Blum <[email protected]>
Signed-off-by: Daisuke Nishimura <[email protected]>
Signed-off-by: Tejun Heo <[email protected]>
Signed-off-by: Greg Kroah-Hartman <[email protected]>
---
kernel/cgroup.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1800,9 +1800,8 @@ static int cgroup_task_migrate(struct cg
* trading it for newcg is protected by cgroup_mutex, we're safe to drop
* it here; it will be freed under RCU.
*/
- put_css_set(oldcg);
-
set_bit(CGRP_RELEASABLE, &oldcgrp->flags);
+ put_css_set(oldcg);
return 0;
}
Patches currently in stable-queue which might be from
[email protected] are
queue-3.0/cgroup-notify_on_release-may-not-be-triggered-in-some-cases.patch
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