diff --git a/rust/kernel/rbtree.rs b/rust/kernel/rbtree.rs
index 6c3b10e46517..b564e4eb733c 100644
--- a/rust/kernel/rbtree.rs
+++ b/rust/kernel/rbtree.rs
@@ -298,56 +298,64 @@ pub fn try_create_and_insert(&mut self, key: K, value: V) -> Result<Option<RBTre
     ///
     /// This function always succeeds.
     pub fn insert(&mut self, node: RBTreeNode<K, V>) -> Option<RBTreeNode<K, V>> {
-        let RBTreeNode { node } = node;
-        let node = Box::into_raw(node);
-        // SAFETY: `node` is valid at least until we call `Box::from_raw`, which only happens when
-        // the node is removed or replaced.
-        let node_links = unsafe { addr_of_mut!((*node).links) };
+        match self.raw_entry(&node.node.key) {
+            RawEntry::Occupied(entry) => Some(entry.replace(node)),
+            RawEntry::Vacant(entry) => {
+                entry.insert(node);
+                None
+            }
+        }
+    }
+
+    fn raw_entry(&mut self, key: &K) -> RawEntry<'_, K, V> {
         let mut new_link: &mut *mut bindings::rb_node = &mut self.root.rb_node;
         let mut parent = core::ptr::null_mut();
-        while !new_link.is_null() {
+        while !(*new_link).is_null() {
+            let curr = *new_link;
             // SAFETY: All links fields we create are in a `Node<K, V>`.
-            let this = unsafe { crate::container_of!(*new_link, Node<K, V>, links) };
+            let node = unsafe { crate::container_of!(curr, Node<K, V>, links) };
 
-            parent = *new_link;
-
-            // SAFETY: `this` is a non-null node so it is valid by the type invariants. `node` is
-            // valid until the node is removed.
-            match unsafe { (*node).key.cmp(&(*this).key) } {
-                // SAFETY: `parent` is a non-null node so it is valid by the type invariants.
-                Ordering::Less => new_link = unsafe { &mut (*parent).rb_left },
-                // SAFETY: `parent` is a non-null node so it is valid by the type invariants.
-                Ordering::Greater => new_link = unsafe { &mut (*parent).rb_right },
+            // SAFETY: `node` is a non-null node so it is valid by the type invariants.
+            match key.cmp(unsafe { &(*node).key }) {
+                // SAFETY: `curr` is a non-null node so it is valid by the type invariants.
+                Ordering::Less => new_link = unsafe { &mut (*curr).rb_left },
+                // SAFETY: `curr` is a non-null node so it is valid by the type invariants.
+                Ordering::Greater => new_link = unsafe { &mut (*curr).rb_right },
                 Ordering::Equal => {
-                    // INVARIANT: We are replacing an existing node with a new one, which is valid.
-                    // It remains valid because we "forgot" it with `Box::into_raw`.
-                    // SAFETY: All pointers are non-null and valid (parent, despite the name, really
-                    // is the node we're replacing).
-                    unsafe { bindings::rb_replace_node(parent, node_links, &mut self.root) };
-
-                    // INVARIANT: The node is being returned and the caller may free it, however,
-                    // it was removed from the tree. So the invariants still hold.
-                    return Some(RBTreeNode {
-                        // SAFETY: `this` was a node in the tree, so it is valid.
-                        node: unsafe { Box::from_raw(this as _) },
-                    });
+                    return RawEntry::Occupied(OccupiedEntry {
+                        rbtree: self,
+                        node_links: curr,
+                    })
                 }
             }
+            parent = curr;
         }
 
-        // INVARIANT: We are linking in a new node, which is valid. It remains valid because we
-        // "forgot" it with `Box::into_raw`.
-        // SAFETY: All pointers are non-null and valid (`*new_link` is null, but `new_link` is a
-        // mutable reference).
-        unsafe { bindings::rb_link_node(node_links, parent, new_link) };
+        RawEntry::Vacant(RawVacantEntry {
+            parent,
+            new_link,
+            rbtree: self,
+        })
+    }
 
-        // SAFETY: All pointers are valid. `node` has just been inserted into the tree.
-        unsafe { bindings::rb_insert_color(node_links, &mut self.root) };
-        None
+    /// Gets the given key's corresponding entry in the map for in-place manipulation.
+    pub fn entry(&mut self, key: K) -> Entry<'_, K, V> {
+        match self.raw_entry(&key) {
+            RawEntry::Occupied(entry) => Entry::Occupied(entry),
+            RawEntry::Vacant(entry) => Entry::Vacant(VacantEntry { raw: entry, key }),
+        }
     }
 
-    /// Returns a node with the given key, if one exists.
-    fn find(&self, key: &K) -> Option<NonNull<Node<K, V>>> {
+    /// Used for accessing the given node, if it exists.
+    pub fn find_mut(&mut self, key: &K) -> Option<OccupiedEntry<'_, K, V>> {
+        match self.raw_entry(key) {
+            RawEntry::Occupied(entry) => Some(entry),
+            RawEntry::Vacant(_entry) => None,
+        }
+    }
+
+    /// Returns a reference to the value corresponding to the key.
+    pub fn get(&self, key: &K) -> Option<&V> {
         let mut node = self.root.rb_node;
         while !node.is_null() {
             // SAFETY: All links fields we create are in a `Node<K, V>`.
@@ -358,54 +366,30 @@ fn find(&self, key: &K) -> Option<NonNull<Node<K, V>>> {
                 Ordering::Less => unsafe { (*node).rb_left },
                 // SAFETY: `node` is a non-null node so it is valid by the type invariants.
                 Ordering::Greater => unsafe { (*node).rb_right },
-                Ordering::Equal => return NonNull::new(this as _),
+                // SAFETY: `node` is a non-null node so it is valid by the type invariants.
+                Ordering::Equal => return Some(unsafe { &(*this).value }),
             }
         }
         None
     }
 
-    /// Returns a reference to the value corresponding to the key.
-    pub fn get(&self, key: &K) -> Option<&V> {
-        // SAFETY: The `find` return value is a node in the tree, so it is valid.
-        self.find(key).map(|node| unsafe { &node.as_ref().value })
-    }
-
     /// Returns a mutable reference to the value corresponding to the key.
     pub fn get_mut(&mut self, key: &K) -> Option<&mut V> {
-        // SAFETY: The `find` return value is a node in the tree, so it is valid.
-        self.find(key)
-            .map(|mut node| unsafe { &mut node.as_mut().value })
+        self.find_mut(key).map(|node| node.into_mut())
     }
 
     /// Removes the node with the given key from the tree.
     ///
     /// It returns the node that was removed if one exists, or [`None`] otherwise.
-    fn remove_node(&mut self, key: &K) -> Option<RBTreeNode<K, V>> {
-        let mut node = self.find(key)?;
-
-        // SAFETY: The `find` return value is a node in the tree, so it is valid.
-        unsafe { bindings::rb_erase(&mut node.as_mut().links, &mut self.root) };
-
-        // INVARIANT: The node is being returned and the caller may free it, however, it was
-        // removed from the tree. So the invariants still hold.
-        Some(RBTreeNode {
-            // SAFETY: The `find` return value was a node in the tree, so it is valid.
-            node: unsafe { Box::from_raw(node.as_ptr()) },
-        })
+    pub fn remove_node(&mut self, key: &K) -> Option<RBTreeNode<K, V>> {
+        self.find_mut(key).map(OccupiedEntry::remove_node)
     }
 
     /// Removes the node with the given key from the tree.
     ///
     /// It returns the value that was removed if one exists, or [`None`] otherwise.
     pub fn remove(&mut self, key: &K) -> Option<V> {
-        let node = self.remove_node(key)?;
-        let RBTreeNode { node } = node;
-        let Node {
-            links: _,
-            key: _,
-            value,
-        } = *node;
-        Some(value)
+        self.find_mut(key).map(OccupiedEntry::remove)
     }
 
     /// Returns a cursor over the tree nodes based on the given key.
@@ -1064,3 +1048,167 @@ unsafe impl<K: Send, V: Send> Send for RBTreeNode<K, V> {}
 // SAFETY: An [`RBTree`] allows the same kinds of access to its values that a struct allows to its
 // fields, so we use the same Sync condition as would be used for a struct with K and V fields.
 unsafe impl<K: Sync, V: Sync> Sync for RBTreeNode<K, V> {}
+
+impl<K, V> RBTreeNode<K, V> {
+    /// "Uninitialises" a node.
+    ///
+    /// It then becomes a reservation that can be re-initialised into a different node (i.e., with
+    /// a different key and/or value).
+    ///
+    /// The existing key and value are dropped in-place as part of this operation, that is, memory
+    /// may be freed (but only for the key/value; memory for the node itself is kept for reuse).
+    pub fn into_reservation(self) -> RBTreeNodeReservation<K, V> {
+        let raw = Box::into_raw(self.node);
+        let mut ret = RBTreeNodeReservation {
+            // SAFETY: The pointer came from a valid `Node`, which has the same layout as
+            // `MaybeUninit<Node>`.
+            node: unsafe { Box::from_raw(raw as _) },
+        };
+        // SAFETY: Although the type is `MaybeUninit<Node>`, we know it has been initialised
+        // because it came from a `Node`. So it is safe to drop it.
+        unsafe { core::ptr::drop_in_place(ret.node.as_mut_ptr()) };
+        ret
+    }
+}
+
+/// A view into a single entry in a map, which may either be vacant or occupied.
+///
+/// This enum is constructed from the [`entry`] method on [`RBTree`].
+///
+/// [`entry`]: fn@RBTree::entry
+pub enum Entry<'a, K, V> {
+    /// This [`RBTree`] does not have a node with this key.
+    Vacant(VacantEntry<'a, K, V>),
+    /// This [`RBTree`] already has a node with this key.
+    Occupied(OccupiedEntry<'a, K, V>),
+}
+
+/// Like [`Entry`], except that it doesn't have ownership of the key.
+enum RawEntry<'a, K, V> {
+    Vacant(RawVacantEntry<'a, K, V>),
+    Occupied(OccupiedEntry<'a, K, V>),
+}
+
+/// A view into a vacant entry in a [`RBTree`]. It is part of the [`Entry`] enum.
+pub struct VacantEntry<'a, K, V> {
+    key: K,
+    raw: RawVacantEntry<'a, K, V>,
+}
+
+/// Like [`VacantEntry`], but doesn't hold on to the key.
+struct RawVacantEntry<'a, K, V> {
+    rbtree: &'a mut RBTree<K, V>,
+    /// The node that will become the parent of the new node if we insert one.
+    ///
+    /// This pointer may be null if the new node becomes the root.
+    parent: *mut bindings::rb_node,
+    /// This points to the left-child or right-child field of `parent`. This controls whether the
+    /// new node will become the left or right child of `parent`.
+    ///
+    /// If `parent` is null, then this points at `rbtree.root`.
+    new_link: *mut *mut bindings::rb_node,
+}
+
+impl<'a, K, V> RawVacantEntry<'a, K, V> {
+    /// Inserts the given node into the [`RBTree`] at this entry.
+    ///
+    /// The `node` must have a key such that inserting it here does not break the ordering of this
+    /// [`RBTree`].
+    fn insert(self, node: RBTreeNode<K, V>) -> &'a mut V {
+        let node = Box::into_raw(node.node);
+
+        // SAFETY: `node` is valid at least until we call `Box::from_raw`, which only happens when
+        // the node is removed or replaced.
+        let node_links = unsafe { addr_of_mut!((*node).links) };
+
+        // INVARIANT: We are linking in a new node, which is valid. It remains valid because we
+        // "forgot" it with `Box::into_raw`.
+        // SAFETY: All pointers are null or valid in an appropriate way.
+        unsafe { bindings::rb_link_node(node_links, self.parent, self.new_link) };
+
+        // SAFETY: All pointers are valid. `node` has just been inserted into the tree.
+        unsafe { bindings::rb_insert_color(node_links, &mut self.rbtree.root) };
+
+        // SAFETY: The node is valid until we remove it from the tree.
+        unsafe { &mut (*node).value }
+    }
+}
+
+impl<'a, K, V> VacantEntry<'a, K, V> {
+    /// Inserts the given node into the [`RBTree`] at this entry.
+    pub fn insert(self, value: V, reservation: RBTreeNodeReservation<K, V>) -> &'a mut V {
+        self.raw.insert(reservation.into_node(self.key, value))
+    }
+}
+
+/// A view into an occupied entry in a [`RBTree`]. It is part of the [`Entry`] enum.
+pub struct OccupiedEntry<'a, K, V> {
+    rbtree: &'a mut RBTree<K, V>,
+    /// The node that this entry corresponds to. Non null.
+    node_links: *mut bindings::rb_node,
+}
+
+impl<'a, K, V> OccupiedEntry<'a, K, V> {
+    fn node_ptr(&self) -> *mut Node<K, V> {
+        // SAFETY: All links fields we create are in a `Node<K, V>`.
+        unsafe { crate::container_of!(self.node_links, Node<K, V>, links) }.cast_mut()
+    }
+
+    /// Gets a reference to the value in the entry.
+    pub fn get(&self) -> &V {
+        unsafe { &(*self.node_ptr()).value }
+    }
+
+    /// Gets a mutable reference to the value in the entry.
+    pub fn get_mut(&mut self) -> &mut V {
+        unsafe { &mut (*self.node_ptr()).value }
+    }
+
+    /// Converts the entry into a mutable reference to its value.
+    ///
+    /// If you need multiple references to the `OccupiedEntry`, see [`self#get_mut`].
+    pub fn into_mut(self) -> &'a mut V {
+        unsafe { &mut (*self.node_ptr()).value }
+    }
+
+    /// Remove this entry from the [`RBTree`].
+    pub fn remove_node(self) -> RBTreeNode<K, V> {
+        // SAFETY: The node is a node in the tree, so it is valid.
+        unsafe { bindings::rb_erase(self.node_links, &mut self.rbtree.root) };
+
+        // INVARIANT: The node is being returned and the caller may free it, however, it was
+        // removed from the tree. So the invariants still hold.
+        RBTreeNode {
+            // SAFETY: The node was a node in the tree, but we removed it, so we can convert it
+            // back into a box.
+            node: unsafe { Box::from_raw(self.node_ptr()) },
+        }
+    }
+
+    /// Takes the value of the entry out of the map, and returns it.
+    pub fn remove(self) -> V {
+        self.remove_node().node.value
+    }
+
+    /// Swap the current node for the provided node.
+    ///
+    /// The key of both nodes must be equal.
+    fn replace(self, node: RBTreeNode<K, V>) -> RBTreeNode<K, V> {
+        let node = Box::into_raw(node.node);
+
+        // SAFETY: `node` is valid at least until we call `Box::from_raw`, which only happens when
+        // the node is removed or replaced.
+        let new_node_links = unsafe { addr_of_mut!((*node).links) };
+
+        // SAFETY: This updates the pointers so that `new_node_links` is in the tree where
+        // `self.node_links` used to be.
+        unsafe {
+            bindings::rb_replace_node(self.node_links, new_node_links, &mut self.rbtree.root)
+        };
+
+        // SAFETY: Now that we removed this entry from the tree, we can convert the node to a box.
+        let old_node = unsafe { Box::from_raw(self.node_ptr()) };
+
+        RBTreeNode { node: old_node }
+    }
+}
