diff options
| author | Tejun Heo <tj@kernel.org> | 2016-01-21 15:32:15 -0500 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2016-05-04 14:48:49 -0700 |
| commit | 3c6266d57c4c4fa02588070347acf21b610bbd96 (patch) | |
| tree | e8915b078cd406a3ce6e81fe857b17a12c600244 /kernel | |
| parent | 36abe7272a248a7e47a4cec8d8ec9c76ef387bac (diff) | |
cgroup: make sure a parent css isn't freed before its children
commit 8bb5ef79bc0f4016ecf79e8dce6096a3c63603e4 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.
The previous patch updated ordering for css_offline() which fixes the
cpu controller issue. While there currently isn't a known bug caused
by misordering of css_free() invocations, let's fix it too for
consistency.
css_free() ordering can be trivially fixed by moving putting of the
parent css below css_free() invocation.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/cgroup.c | 7 |
1 files changed, 4 insertions, 3 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c index b0ea3aebc05a..1c9d701f7a72 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -4692,14 +4692,15 @@ static void css_free_work_fn(struct work_struct *work) if (ss) { /* css free path */ + struct cgroup_subsys_state *parent = css->parent; int id = css->id; - if (css->parent) - css_put(css->parent); - ss->css_free(css); cgroup_idr_remove(&ss->css_idr, id); cgroup_put(cgrp); + + if (parent) + css_put(parent); } else { /* cgroup free path */ atomic_dec(&cgrp->root->nr_cgrps); |