[AMD] Fall back to CPU tensor for decode retraction on ROCm (#36343)

python/sglang/srt/mem_cache/kv_cache_builder.py

@@ -47,6 +47,7 @@ from sglang.srt.runtime_context import (
     get_parallel,
     get_schedule,
 )
+from sglang.srt.utils import is_hip
 
 if TYPE_CHECKING:
 
@@ -143,6 +144,9 @@ def resolve_decode_retraction_backup(*, tp_worker: BaseTpWorker) -> str:
         backend = (
             "host_pool"
             if disagg.disaggregation_mode == "decode"
+            # Large ROCm retraction restores can fault the GPU process. Keep
+            # host_pool opt-in on HIP until the retraction path is safe at scale.
+            and not is_hip()
             and not get_parallel().dcp_enabled
             and not disagg.disaggregation_decode_enable_radix_cache
             # KV offload already owns a host pool; a second one double-books host memory.