diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 940aced..2206151 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -4084,6 +4084,9 @@ static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos)
 	int index = 0, pid = *pos;
 	int *iter, ret;
 
+	if (!cgroup_tryget(cgrp))
+		return NULL;
+
 	mutex_lock(&cgrp->pidlist_mutex);
 
 	/*
@@ -4132,13 +4135,15 @@ static void *cgroup_pidlist_start(struct seq_file *s, loff_t *pos)
 
 static void cgroup_pidlist_stop(struct seq_file *s, void *v)
 {
+	struct cgroup *cgrp = seq_css(s)->cgroup;
 	struct kernfs_open_file *of = s->private;
 	struct cgroup_pidlist *l = of->priv;
 
 	if (l)
 		mod_delayed_work(cgroup_pidlist_destroy_wq, &l->destroy_dwork,
 				 CGROUP_PIDLIST_DESTROY_DELAY);
-	mutex_unlock(&seq_css(s)->cgroup->pidlist_mutex);
+	mutex_unlock(&cgrp->pidlist_mutex);
+	cgroup_put(cgrp);
 }
 
 static void *cgroup_pidlist_next(struct seq_file *s, void *v, loff_t *pos)