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authorDaisuke Nishimura <nishimura@mxp.nes.nec.co.jp>2012-10-04 16:37:16 +0900
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2012-10-28 10:02:12 -0700
commitf0c76f5fa97e436cf24cb57a4aeceb7c83835704 (patch)
tree9e6dbc01002309148f9a38d83036699c67fc1d15 /kernel
parent68e919c11e940d2d2d34a6a6beae28d62a439f55 (diff)
cgroup: notify_on_release may not be triggered in some cases
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 <lizefan@huawei.com> Cc: Ben Blum <bblum@andrew.cmu.edu> Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel')
-rw-r--r--kernel/cgroup.c3
1 files changed, 1 insertions, 2 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 2efce77f649c..69158d5b02eb 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -1800,9 +1800,8 @@ static int cgroup_task_migrate(struct cgroup *cgrp, struct cgroup *oldcgrp,
* 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;
}