From e40c0422808d8a5e1c633d1170a171894e9d040f Mon Sep 17 00:00:00 2001
From: Xintong Li <znculee@gmail.com>
Date: Mon, 6 Apr 2026 21:14:13 -0700
Subject: [PATCH] fix missing position_ids in log-prob forward step

---
 slime/backends/megatron_utils/model.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/slime/backends/megatron_utils/model.py b/slime/backends/megatron_utils/model.py
index ffe3f06ba2..3b70162446 100644
--- a/slime/backends/megatron_utils/model.py
+++ b/slime/backends/megatron_utils/model.py
@@ -226,6 +226,7 @@ def forward_step(
         response_lengths = batch["response_lengths"]
         forward_kwargs = {
             "input_ids": tokens,
+            "position_ids": None,
             "attention_mask": None,
             "labels": None,
             "packed_seq_params": packed_seq_params,