--- y/include/linux/cgroup-defs.h
+++ x/include/linux/cgroup-defs.h
@@ -179,7 +179,7 @@ struct cgroup_subsys_state {
 	atomic_t online_cnt;
 
 	/* percpu_ref killing and RCU release */
-	struct work_struct destroy_work;
+	struct work_struct destroy_work, release_work;
 	struct rcu_work destroy_rwork;
 
 	/*
--- y/kernel/cgroup/cgroup.c
+++ x/kernel/cgroup/cgroup.c
@@ -5154,7 +5154,7 @@ static void css_free_rwork_fn(struct wor
 static void css_release_work_fn(struct work_struct *work)
 {
 	struct cgroup_subsys_state *css =
-		container_of(work, struct cgroup_subsys_state, destroy_work);
+		container_of(work, struct cgroup_subsys_state, release_work);
 	struct cgroup_subsys *ss = css->ss;
 	struct cgroup *cgrp = css->cgroup;
 
@@ -5210,8 +5210,8 @@ static void css_release(struct percpu_re
 	struct cgroup_subsys_state *css =
 		container_of(ref, struct cgroup_subsys_state, refcnt);
 
-	INIT_WORK(&css->destroy_work, css_release_work_fn);
-	queue_work(cgroup_destroy_wq, &css->destroy_work);
+	INIT_WORK(&css->release_work, css_release_work_fn);
+	queue_work(cgroup_destroy_wq, &css->release_work);
 }
 
 static void init_and_link_css(struct cgroup_subsys_state *css,
--- y/fs/namespace.c
+++ x/fs/namespace.c
@@ -215,7 +215,7 @@ static struct mount *alloc_vfsmnt(const
 		if (!mnt->mnt_pcp)
 			goto out_free_devname;
 
-		this_cpu_add(mnt->mnt_pcp->mnt_count, 1);
+		this_cpu_add(mnt->mnt_pcp->mnt_count, 2);
 #else
 		mnt->mnt_count = 1;
 		mnt->mnt_writers = 0;
@@ -1221,10 +1221,16 @@ static void mntput_no_expire(struct moun
 		 * we are dropping is not the final one.
 		 */
 		mnt_add_count(mnt, -1);
+		count = mnt_get_count(mnt);
+		WARN_ON(count == 0);
+		WARN_ON(count < 0);
 		rcu_read_unlock();
 		return;
 	}
 	lock_mount_hash();
+	count = mnt_get_count(mnt);
+	WARN_ON(count == 0);
+	WARN_ON(count < 0);
 	/*
 	 * make sure that if __legitimize_mnt() has not seen us grab
 	 * mount_lock, we'll see their refcount increment here.