There was a long-standing bug that this function was called without any
lock. Add a check to prevent similar issue.
Signed-off-by: Li Zefan <lizefan@xxxxxxxxxx>
---
kernel/cgroup.c | 15 +++++++++++----
1 file changed, 11 insertions(+), 4 deletions(-)
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 776ff75..3d21adf 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -5028,13 +5028,20 @@ int cgroup_is_descendant(const struct cgroup *cgrp, struct task_struct *task)
static void check_for_release(struct cgroup *cgrp)
{
- /* All of these checks rely on RCU to keep the cgroup
- * structure alive */
+ /*
+ * All of these checks rely on RCU or cgroup_mutex to keep the cgroup
+ * structure alive
+ */
+ rcu_lockdep_assert(rcu_read_lock_held() || cgroup_lock_is_held(),
+ "check_for_release() called witout proper locking");
+
if (cgroup_is_releasable(cgrp) && !atomic_read(&cgrp->count)
&& list_empty(&cgrp->children) && !cgroup_has_css_refs(cgrp)) {
- /* Control Group is currently removeable. If it's not
+ /*
+ * Control Group is currently removable. If it's not
* already queued for a userspace notification, queue
- * it now */
+ * it now
+ */
int need_schedule_work = 0;
raw_spin_lock(&release_list_lock);
if (!cgroup_is_removed(cgrp) &&
--
1.8.0.2
--
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