diff --git a/tokio/src/runtime/task/list.rs b/tokio/src/runtime/task/list.rs
index 265c91b27a7..44873540986 100644
--- a/tokio/src/runtime/task/list.rs
+++ b/tokio/src/runtime/task/list.rs
@@ -187,6 +187,7 @@ impl<S: 'static> OwnedTasks<S> {
 
 cfg_taskdump! {
     impl<S: 'static> OwnedTasks<S> {
+        /// Locks the tasks, and calls `f` on an iterator over them.
         pub(crate) fn for_each<F>(&self, f: F)
         where
             F: FnMut(&Task<S>),
diff --git a/tokio/src/util/linked_list.rs b/tokio/src/util/linked_list.rs
index dab9828ccbd..0ed2b616456 100644
--- a/tokio/src/util/linked_list.rs
+++ b/tokio/src/util/linked_list.rs
@@ -296,7 +296,7 @@ cfg_io_driver_impl! {
 
 cfg_taskdump! {
     impl<T: Link> LinkedList<T, T::Target> {
-        pub(crate) fn for_each<F>(&mut self, f: &mut F)
+        pub(crate) fn for_each<F>(&mut self, mut f: F)
         where
             F: FnMut(&T::Handle),
         {