diff options
| author | Tejun Heo <tj@kernel.org> | 2016-01-21 15:31:11 -0500 |
|---|---|---|
| committer | Luis Henriques <luis.henriques@canonical.com> | 2016-02-25 00:18:35 +0000 |
| commit | d9892cc2d91b31ea58c775531813a21dc24e50d0 (patch) | |
| tree | c183211e03784804cea70af633b82786703f8a8b /include/linux | |
| parent | 65284f9e75bc1179166d045b164f4872b6e85032 (diff) | |
cgroup: make sure a parent css isn't offlined before its children
commit aa226ff4a1ce79f229c6b7a4c0a14e17fececd01 upstream.
There are three subsystem callbacks in css shutdown path -
css_offline(), css_released() and css_free(). Except for
css_released(), cgroup core didn't guarantee the order of invocation.
css_offline() or css_free() could be called on a parent css before its
children. This behavior is unexpected and led to bugs in cpu and
memory controller.
This patch updates offline path so that a parent css is never offlined
before its children. Each css keeps online_cnt which reaches zero iff
itself and all its children are offline and offline_css() is invoked
only after online_cnt reaches zero.
This fixes the memory controller bug and allows the fix for cpu
controller.
Signed-off-by: Tejun Heo <tj@kernel.org>
Reported-and-tested-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reported-by: Brian Christiansen <brian.o.christiansen@gmail.com>
Link: http://lkml.kernel.org/g/5698A023.9070703@de.ibm.com
Link: http://lkml.kernel.org/g/CAKB58ikDkzc8REt31WBkD99+hxNzjK4+FBmhkgS+NVrC9vjMSg@mail.gmail.com
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Peter Zijlstra <peterz@infradead.org>
[ luis: backported to 3.16:
- file rename: cgroup-defs.h -> cgroup.h
- adjusted context ]
Signed-off-by: Luis Henriques <luis.henriques@canonical.com>
Diffstat (limited to 'include/linux')
| -rw-r--r-- | include/linux/cgroup.h | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h index 8a111dd42d7a..c2d312de22f8 100644 --- a/include/linux/cgroup.h +++ b/include/linux/cgroup.h @@ -88,6 +88,12 @@ struct cgroup_subsys_state { */ u64 serial_nr; + /* + * Incremented by online self and children. Used to guarantee that + * parents are not offlined before their children. + */ + atomic_t online_cnt; + /* percpu_ref killing and RCU release */ struct rcu_head rcu_head; struct work_struct destroy_work; |