| From | Herton Ronaldo Krzesinski <> | Subject | [PATCH 189/270] cgroup: notify_on_release may not be triggered in some cases | Date | Mon, 26 Nov 2012 14:57:59 -0200 |
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3.5.7u1 -stable review patch. If anyone has any objections, please let me know.
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From: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
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.
Cc: Ben Blum <bblum@andrew.cmu.edu> Acked-by: Li Zefan <lizefan@huawei.com> Signed-off-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp> Signed-off-by: Tejun Heo <tj@kernel.org> Signed-off-by: Herton Ronaldo Krzesinski <herton.krzesinski@canonical.com> --- kernel/cgroup.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 15462a0..63c9596 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -1927,9 +1927,8 @@ static void 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); } /** -- 1.7.9.5
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