diff --git a/keystone/assignment/core.py b/keystone/assignment/core.py
index 6d2025d530..a79fd18ff4 100644
--- a/keystone/assignment/core.py
+++ b/keystone/assignment/core.py
@@ -938,6 +938,7 @@ class Manager(manager.Manager):
 
         return assignments
 
+    @MEMOIZE_COMPUTED_ASSIGNMENTS
     def list_role_assignments(self, role_id=None, user_id=None, group_id=None,
                               system=None, domain_id=None, project_id=None,
                               include_subtree=False, inherited=None,
@@ -1080,6 +1081,7 @@ class Manager(manager.Manager):
         system_assignments = self.list_system_grants_for_group(group_id)
         for assignment in system_assignments:
             self.delete_system_grant_for_group(group_id, assignment['id'])
+        COMPUTED_ASSIGNMENTS_REGION.invalidate()
 
     def delete_user_assignments(self, user_id):
         # FIXME(lbragstad): This should be refactored in the Rocky release so
@@ -1091,6 +1093,7 @@ class Manager(manager.Manager):
         system_assignments = self.list_system_grants_for_user(user_id)
         for assignment in system_assignments:
             self.delete_system_grant_for_user(user_id, assignment['id'])
+        COMPUTED_ASSIGNMENTS_REGION.invalidate()
 
     def check_system_grant_for_user(self, user_id, role_id):
         """Check if a user has a specific role on the system.
@@ -1163,6 +1166,7 @@ class Manager(manager.Manager):
         target_id = self._SYSTEM_SCOPE_TOKEN
         inherited = False
         self.driver.delete_system_grant(role_id, user_id, target_id, inherited)
+        COMPUTED_ASSIGNMENTS_REGION.invalidate()
 
     def check_system_grant_for_group(self, group_id, role_id):
         """Check if a group has a specific role on the system.
@@ -1237,6 +1241,7 @@ class Manager(manager.Manager):
         self.driver.delete_system_grant(
             role_id, group_id, target_id, inherited
         )
+        COMPUTED_ASSIGNMENTS_REGION.invalidate()
 
     def list_all_system_grants(self):
         """Return a list of all system grants."""
diff --git a/keystone/models/revoke_model.py b/keystone/models/revoke_model.py
index 63425f1adc..c36d4fdc30 100644
--- a/keystone/models/revoke_model.py
+++ b/keystone/models/revoke_model.py
@@ -242,8 +242,9 @@ def build_token_values(token):
         token_values['assignment_domain_id'] = None
 
     role_list = []
-    if token.roles is not None:
-        for role in token.roles:
+    token_roles = token.roles
+    if token_roles is not None:
+        for role in token_roles:
             role_list.append(role['id'])
     token_values['roles'] = role_list
 
diff --git a/keystone/tests/unit/assignment/test_backends.py b/keystone/tests/unit/assignment/test_backends.py
index 4add5649a0..119bcf7ab3 100644
--- a/keystone/tests/unit/assignment/test_backends.py
+++ b/keystone/tests/unit/assignment/test_backends.py
@@ -643,6 +643,9 @@ class AssignmentTests(AssignmentTestHelperMixin):
         # attempts to lookup a group that has been deleted in the backend
         with mock.patch.object(PROVIDERS.identity_api, 'get_group',
                                _group_not_found):
+            # Mocking a dependent function makes the cache invalid
+            keystone.assignment.COMPUTED_ASSIGNMENTS_REGION.invalidate()
+
             assignment_list = PROVIDERS.assignment_api.list_role_assignments(
                 include_names=True
             )
@@ -669,6 +672,9 @@ class AssignmentTests(AssignmentTestHelperMixin):
         # in the backend
         with mock.patch.object(PROVIDERS.identity_api, 'list_users_in_group',
                                _group_not_found):
+            # Mocking a dependent function makes the cache invalid
+            keystone.assignment.COMPUTED_ASSIGNMENTS_REGION.invalidate()
+
             assignment_list = PROVIDERS.assignment_api.list_role_assignments(
                 effective=True
             )