diff options
| author | Waiman Long <longman@redhat.com> | 2017-05-15 09:34:06 -0400 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2017-05-17 16:58:32 -0400 |
| commit | 33c35aa4817864e056fd772230b0c6b552e36ea2 (patch) | |
| tree | c5eea540e4e818e11aa809d7652cface407203e7 | |
| parent | 2ea659a9ef488125eb46da6eb571de5eae5c43f6 (diff) | |
cgroup: Prevent kill_css() from being called more than once
The kill_css() function may be called more than once under the condition
that the css was killed but not physically removed yet followed by the
removal of the cgroup that is hosting the css. This patch prevents any
harmm from being done when that happens.
Signed-off-by: Waiman Long <longman@redhat.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: stable@vger.kernel.org # v4.5+
| -rw-r--r-- | include/linux/cgroup-defs.h | 1 | ||||
| -rw-r--r-- | kernel/cgroup/cgroup.c | 5 |
2 files changed, 6 insertions, 0 deletions
diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h index 21745946cae1..ec47101cb1bf 100644 --- a/include/linux/cgroup-defs.h +++ b/include/linux/cgroup-defs.h @@ -48,6 +48,7 @@ enum { CSS_ONLINE = (1 << 1), /* between ->css_online() and ->css_offline() */ CSS_RELEASED = (1 << 2), /* refcnt reached zero, released */ CSS_VISIBLE = (1 << 3), /* css is visible to userland */ + CSS_DYING = (1 << 4), /* css is dying */ }; /* bits in struct cgroup flags field */ diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c index c3c9a0e1b3c9..8d4e85eae42c 100644 --- a/kernel/cgroup/cgroup.c +++ b/kernel/cgroup/cgroup.c @@ -4265,6 +4265,11 @@ static void kill_css(struct cgroup_subsys_state *css) { lockdep_assert_held(&cgroup_mutex); + if (css->flags & CSS_DYING) + return; + + css->flags |= CSS_DYING; + /* * This must happen before css is disassociated with its cgroup. * See seq_css() for details. |