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-rw-r--r--kernel/cgroup.c10
1 files changed, 10 insertions, 0 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index fd38e1cfacca..65b72d0367c5 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -876,6 +876,13 @@ static void cgroup_free_fn(struct work_struct *work)
mutex_unlock(&cgroup_mutex);
/*
+ * We get a ref to the parent's dentry, and put the ref when
+ * this cgroup is being freed, so it's guaranteed that the
+ * parent won't be destroyed before its children.
+ */
+ dput(cgrp->parent->dentry);
+
+ /*
* Drop the active superblock reference that we took when we
* created the cgroup
*/
@@ -4164,6 +4171,9 @@ static long cgroup_create(struct cgroup *parent, struct dentry *dentry,
for_each_subsys(root, ss)
dget(dentry);
+ /* hold a ref to the parent's dentry */
+ dget(parent->dentry);
+
/* creation succeeded, notify subsystems */
for_each_subsys(root, ss) {
err = online_css(ss, cgrp);