diff --git a/Documentation/netlink/specs/rt-route.yaml b/Documentation/netlink/specs/rt-route.yaml
index 9f4a1a253676..253037ea5176 100644
--- a/Documentation/netlink/specs/rt-route.yaml
+++ b/Documentation/netlink/specs/rt-route.yaml
@@ -78,6 +78,27 @@ definitions:
       -
         name: rta-used
         type: u32
+  -
+    name: del-reason
+    type: enum
+    name-prefix: rt-del-reason-
+    enum-name: rt-del-reason
+    doc: |
+      Why the kernel deleted a route. New causes may be appended. The
+      value space is family-agnostic, a value is never reinterpreted
+      per address family.
+    entries:
+      -
+        name: unspec
+        doc: The deletion path does not record a cause.
+      -
+        name: expired
+        doc: The RTF_EXPIRES lifetime ran out and the route was garbage
+          collected.
+      -
+        name: ra-withdrawn
+        doc: A Router Advertisement withdrew the route with a zero
+          lifetime.
 
 attribute-sets:
   -
@@ -185,6 +206,18 @@ attribute-sets:
         type: u32
         byte-order: big-endian
         display-hint: hex
+      -
+        name: del-reason
+        type: u32
+        enum: del-reason
+        doc: |
+          Emitted only on RTM_DELROUTE notifications, and only when the
+          deletion path records a cause. An absent attribute means
+          either an older kernel or a deletion path that does not
+          record its cause, consumers must treat absent and unspec
+          identically. Currently only IPv6 deletion paths record a
+          cause. The attribute is notification-only, the kernel rejects
+          it in requests.
   -
     name: metrics
     name-prefix: rtax-
@@ -299,6 +332,7 @@ operations:
             - dport
             - nh-id
             - flowlabel
+            - del-reason
       dump:
         request:
           value: 26