diff --git a/django/db/transaction.py b/django/db/transaction.py
index 5d80bf24f03f3..61238fa911ebd 100644
--- a/django/db/transaction.py
+++ b/django/db/transaction.py
@@ -245,7 +245,11 @@ def _commit_on_success(*args, **kw):
                 raise
             else:
                 if is_dirty():
-                    commit()
+                    try:
+                        commit()
+                    except:
+                        rollback()
+                        raise
             return res
         finally:
             leave_transaction_management()
diff --git a/tests/modeltests/transactions/models.py b/tests/modeltests/transactions/models.py
index 6763144ca5d08..9f32776f26191 100644
--- a/tests/modeltests/transactions/models.py
+++ b/tests/modeltests/transactions/models.py
@@ -100,3 +100,23 @@ def __unicode__(self):
     ...
 TransactionManagementError: Transaction managed block ended with pending COMMIT/ROLLBACK
 """
+
+# Regression for #11900: If a function wrapped by commit_on_success writes a
+# transaction that can't be committed, that transaction should be rolled back.
+# The bug is only visible using the psycopg2 backend, though
+# the fix is generally a good idea.
+if building_docs or settings.DATABASE_ENGINE == 'postgresql_psycopg2':
+    __test__['API_TESTS'] += """
+>>> def execute_bad_sql():
+...     cursor = connection.cursor()
+...     cursor.execute("INSERT INTO transactions_reporter (first_name, last_name) VALUES ('Douglas', 'Adams');")
+...     transaction.set_dirty()
+...
+>>> execute_bad_sql = transaction.commit_on_success(execute_bad_sql)
+>>> execute_bad_sql()
+Traceback (most recent call last):
+    ...
+IntegrityError: null value in column "email" violates not-null constraint
+<BLANKLINE>
+
+"""