[Bugfix] Qwen3-Omni thinker: create deepstack buffers on the real device (#8461)

Signed-off-by: John Nunez <johnnynunez@users.noreply.github.com>
Co-authored-by: John Nunez <johnnynunez@users.noreply.github.com>
Co-authored-by: amy-why-3459 <wuhaiyan17@huawei.com>

vllm_omni/model_executor/models/qwen3_omni/qwen3_omni_moe_thinker.py

@@ -1143,10 +1143,17 @@ class Qwen3OmniMoeThinkerForConditionalGeneration(
 
             # register buffer for deepstack
             if self.use_deepstack:
+                # Create the buffers on the target device explicitly. They are
+                # built inside the `_mark_tower_model` block, which runs under
+                # vLLM's meta-device `no_init_weights` context when the image and
+                # video limits are both 0 (audio-only serving), so a bare
+                # torch.zeros(...) would stay on meta and the first profile_run
+                # fails with "Tensor on device meta is not on the expected device".
                 self.deepstack_input_embeds = [
                     torch.zeros(
                         vllm_config.scheduler_config.max_num_batched_tokens,
                         thinker_config.text_config.hidden_size,
+                        device=vllm_config.device_config.device,
                     )
                     for _ in range(self.deepstack_num_level)
                 ]