[BugFix] Fix prefill memory leak in PD + GDN (#12994)

python/sglang/srt/disaggregation/prefill.py

@@ -612,7 +612,12 @@ class SchedulerDisaggregationPrefillMixin:
                 else:
                     self.send_kv_chunk(self.chunked_req)
                 # chunked request keeps its rid but will get a new req_pool_idx
-                self.req_to_token_pool.free(self.chunked_req.req_pool_idx)
+                if self.tp_worker.model_runner.mambaish_config is not None:
+                    self.req_to_token_pool.free(
+                        self.chunked_req.req_pool_idx, free_mamba_cache=False
+                    )
+                else:
+                    self.req_to_token_pool.free(self.chunked_req.req_pool_idx)
                 self.running_batch.batch_is_full = False
 
     def send_kv_chunk(