diff --git a/fs/file.c b/fs/file.c
index 58f4acb5c8624393c1c6b1a9e9a64372389e585f..3b99457518ef5fc4933ae7d53a7b136af386483c 100644
--- a/fs/file.c
+++ b/fs/file.c
@@ -374,8 +374,12 @@ struct files_struct *dup_fd(struct files_struct *oldf, unsigned int max_fds, int
 
 	rcu_assign_pointer(newf->fdt, new_fdt);
 #ifdef CONFIG_CGROUP_FILES
-	if (!files_cgroup_alloc_fd(newf, files_cgroup_count_fds(newf)))
+	spin_lock(&newf->file_lock);
+	if (!files_cgroup_alloc_fd(newf, files_cgroup_count_fds(newf))) {
+		spin_unlock(&newf->file_lock);
 		return newf;
+	}
+	spin_unlock(&newf->file_lock);
 
 /* could not get enough FD resources.  Need to clean up. */
 	new_fds = new_fdt->fd;