Fix dummy weight init for tensor subclasses (#29229)

2026-06-29 01:17:00 +08:00
parent c5b9388721
commit ad30a9958e
1 changed files with 4 additions and 1 deletions
@@ -1469,7 +1469,10 @@ def initialize_dummy_weights(
        if torch.is_floating_point(param):
            generator = torch.Generator(device=param.data.device)
            generator.manual_seed(seed)
-            if torch.finfo(param.data.dtype).bits < 16:
+            # Tensor subclasses such as MXFP8 wrappers expose a low-bit raw
+            # storage dtype through `.data`, but their wrapper `uniform_` also
+            # updates side tensors such as block scales.
+            if torch.finfo(param.dtype).bits < 16:
                # uniform_ doesn't support < 16-bit datatypes (FP8)
                dtype = param.data.dtype
                tmp_param = param.data.to(torch.float16)