Remove FlashInfer GB transport workaround (#27453)

Signed-off-by: Mohammad Miadh Angkad <176301910+mmangkad@users.noreply.github.com>

python/sglang/srt/environ.py

@@ -509,9 +509,6 @@ class Envs:
     # None = standard attention. See https://arxiv.org/abs/2512.12087
     SGLANG_SKIP_SOFTMAX_PREFILL_THRESHOLD_SCALE_FACTOR = EnvFloat(None)
     SGLANG_SKIP_SOFTMAX_DECODE_THRESHOLD_SCALE_FACTOR = EnvFloat(None)
-    # TODO(mmangkad): Remove this once the FlashInfer unified allreduce-fusion
-    # transport issue on GB200/GB300 platforms is fixed and verified resolved.
-    SGLANG_FLASHINFER_FORCE_POSIX_FD_TRANSPORT = EnvBool(None)
 
     # Triton
     SGLANG_TRITON_DECODE_ATTN_STATIC_KV_SPLITS = EnvBool(False)

python/sglang/srt/layers/flashinfer_comm_fusion.py

@@ -1,7 +1,5 @@
-import contextlib
 import inspect
 import logging
-import platform
 from typing import Optional, Tuple
 
 import torch
@@ -18,7 +16,6 @@ from sglang.srt.distributed import (
     get_moe_tp_group,
     get_tp_group,
 )
-from sglang.srt.environ import envs
 from sglang.srt.utils import (
     ceil_align,
     get_cuda_driver_bindings,
@@ -34,72 +31,6 @@ _flashinfer_allreduce_unavailable = False
 _flashinfer_create_workspace_supports_group = False
 _flashinfer_create_workspace_supports_comm_backend = False
 _flashinfer_allreduce_supports_trigger_completion = False
-_posix_transport_override_logged = False
-
-
-def _should_force_posix_fd_transport() -> bool:
-    force_posix_env = envs.SGLANG_FLASHINFER_FORCE_POSIX_FD_TRANSPORT.get()
-    if force_posix_env is not None:
-        return force_posix_env
-
-    machine = platform.machine().lower()
-    if machine not in ("aarch64", "arm64"):
-        return False
-
-    if not torch.cuda.is_available():
-        return False
-
-    try:
-        major, _minor = torch.cuda.get_device_capability(torch.cuda.current_device())
-    except Exception as e:
-        logger.debug("Failed to get CUDA device capability: %s", e)
-        return False
-
-    return major == 10
-
-
-@contextlib.contextmanager
-def _flashinfer_posix_fd_transport_override_if_needed():
-    # TODO(mmangkad): Remove this temporary override once the
-    # FlashInfer unified allreduce-fusion transport issue on
-    # GB200/GB300 platforms is fixed and verified resolved.
-    global _posix_transport_override_logged
-
-    if not _should_force_posix_fd_transport():
-        yield
-        return
-
-    try:
-        import flashinfer.comm.mnnvl as flashinfer_mnnvl
-    except Exception as e:
-        logger.debug(
-            "Failed to import flashinfer.comm.mnnvl for transport override: %s", e
-        )
-        yield
-        return
-
-    original_checker = getattr(flashinfer_mnnvl, "is_mnnvl_fabric_supported", None)
-    if original_checker is None:
-        yield
-        return
-
-    if not _posix_transport_override_logged:
-        logger.warning(
-            "Applying FlashInfer transport workaround: forcing PosixFD "
-            "symmetric-memory handle exchange on aarch64 + sm10x to avoid "
-            "known data corruption with Fabric handle exchange on GB systems. "
-            "Set SGLANG_FLASHINFER_FORCE_POSIX_FD_TRANSPORT=0 to disable."
-        )
-        _posix_transport_override_logged = True
-
-    def _always_disable_fabric(_device_idx: int) -> bool:
-        return False
-
-    flashinfer_mnnvl.is_mnnvl_fabric_supported = _always_disable_fabric
-    try:
-        yield
-    finally:
-        flashinfer_mnnvl.is_mnnvl_fabric_supported = original_checker
 
 
 if is_flashinfer_available():
@@ -177,21 +108,13 @@ def is_flashinfer_allreduce_unavailable() -> bool:
 
 
 def _make_flashinfer_workspace_allocation_prop(cuda_driver):
-    if _should_force_posix_fd_transport():
+    from flashinfer.comm.mnnvl import is_mnnvl_fabric_supported
-        handle_type = (
-            cuda_driver.CUmemAllocationHandleType.CU_MEM_HANDLE_TYPE_POSIX_FILE_DESCRIPTOR
-        )
-    else:
-        from flashinfer.comm.mnnvl import is_mnnvl_fabric_supported
 
-        if is_mnnvl_fabric_supported(torch.cuda.current_device()):
+    handle_types = cuda_driver.CUmemAllocationHandleType
-            handle_type = (
+    if is_mnnvl_fabric_supported(torch.cuda.current_device()):
-                cuda_driver.CUmemAllocationHandleType.CU_MEM_HANDLE_TYPE_FABRIC
+        handle_type = handle_types.CU_MEM_HANDLE_TYPE_FABRIC
-            )
+    else:
-        else:
+        handle_type = handle_types.CU_MEM_HANDLE_TYPE_POSIX_FILE_DESCRIPTOR
-            handle_type = (
-                cuda_driver.CUmemAllocationHandleType.CU_MEM_HANDLE_TYPE_POSIX_FILE_DESCRIPTOR
-            )
 
     prop = cuda_driver.CUmemAllocationProp()
     prop.requestedHandleTypes = handle_type
@@ -413,8 +336,7 @@ class FlashInferWorkspaceManager:
                 kwargs["comm_backend"] = _TorchDistBackend(
                     device_group=device_group, cpu_group=cpu_group
                 )
-            with _flashinfer_posix_fd_transport_override_if_needed():
+            self.workspace = create_workspace(**kwargs)
-                self.workspace = create_workspace(**kwargs)
         except Exception as e:
             _flashinfer_allreduce_unavailable = True
             logger.warning(