[Fix][AMD] MoRI EP: drop record_stream in TBO dispatch/combine (HSA out-of-resources) (#32746)

Co-authored-by: billishyahao <bill.he@amd.com>
Co-authored-by: Duyi-Wang <duyi.wang@amd.com>

python/sglang/srt/layers/moe/token_dispatcher/moriep.py

@@ -669,10 +669,15 @@ class _MoriEPDispatcherImplNormal(_MoriEPDispatcherImplBase):
             compute_stream = torch.cuda.current_stream()
             comm_stream = self._comm_stream  # comm stream
 
-            for t in (hidden_states, topk_weights, topk_ids):
+            # Deliberately no `record_stream(comm_stream)`: it would hold every
-                t.record_stream(comm_stream)
+            # dispatch/combine block in the allocator's deferred-free list until
-            if scale is not None:
+            # the comm event retires, and with `async_finish` the compute stream
-                scale.record_stream(comm_stream)
+            # never blocks, so `reserved` churns until ROCr runs out of scratch
+            # (HSA_STATUS_ERROR_OUT_OF_RESOURCES) -- the failure the non-EP DP
+            # TBO path already hit, see `_TBO_PERSIST_BUF` in dp_attention.py.
+            # Dropping it outright (rather than a keep-alive as in DeepseekV4
+            # op_combine_a) is safe because dispatch_b / combine_b wait_event on
+            # the compute stream in the same call, with no TBO yield between.
 
             with torch.cuda.stream(comm_stream):
                 # if (previous_event) stream_wait(comm_stream, previous_event)
@@ -710,14 +715,6 @@ class _MoriEPDispatcherImplNormal(_MoriEPDispatcherImplBase):
                 else:
                     compute_stream.wait_stream(comm_stream)
 
-            for t in (
-                packed_recv_hidden,
-                recv_topk_weights,
-                recv_scales,
-                recv_topk_ids,
-            ):
-                if t is not None:
-                    t.record_stream(comm_stream)
         else:
 
             (
@@ -783,8 +780,7 @@ class _MoriEPDispatcherImplNormal(_MoriEPDispatcherImplBase):
             compute_stream = torch.cuda.current_stream()
             comm_stream = self._comm_stream
 
-            for t in (hidden_states, topk_ids, topk_weights):
+            # No `record_stream(comm_stream)` -- see `_dispatch_core`.
-                t.record_stream(comm_stream)
 
             with torch.cuda.stream(comm_stream):
                 if previous_event is not None:
@@ -810,8 +806,6 @@ class _MoriEPDispatcherImplNormal(_MoriEPDispatcherImplBase):
                 else:
                     compute_stream.wait_stream(comm_stream)
 
-            combined_hidden_states.record_stream(comm_stream)
-
         else:
             combine_kwargs = self._combine_kwargs(hidden_states)
             combined_hidden_states = self.mori_op.combine(