diff --git a/vllm/v1/attention/backends/mla/common.py b/vllm/v1/attention/backends/mla/common.py
index fa9e94ad189ac..d82afa5b630fd 100644
--- a/vllm/v1/attention/backends/mla/common.py
+++ b/vllm/v1/attention/backends/mla/common.py
@@ -485,14 +485,11 @@ class MLACommonMetadataBuilder(AttentionMetadataBuilder[M]):
         device = self.runner.device
         block_table = self.block_table
         block_table_tensor = block_table.get_device_tensor()[req_slice]
-        slot_mapping = block_table.slot_mapping_cpu[token_slice].to(
-            device, non_blocking=True).long()
-        # block_table_tensor = block_table.get_device_tensor()[:num_reqs]
-        # block_table.slot_mapping[:num_actual_tokens].copy_(
-        #     block_table.slot_mapping_cpu[:num_actual_tokens],
-        #     non_blocking=True)
-        # block_table.slot_mapping[num_actual_tokens:].fill_(-1)
-        # slot_mapping = block_table.slot_mapping[:num_actual_tokens]
+        block_table.slot_mapping[token_slice].copy_(
+            block_table.slot_mapping_cpu[token_slice],
+            non_blocking=True)
+        block_table.slot_mapping[token_slice.stop:].fill_(-1)
+        slot_mapping = block_table.slot_mapping[token_slice]
 
         query_start_loc = slice_query_start_locs(
             common_attn_metadata.query_start_loc, req_slice)