diff --git a/python/sglang/srt/model_executor/model_runner_kv_cache_mixin.py b/python/sglang/srt/model_executor/model_runner_kv_cache_mixin.py
index 7662dee1d..98559e226 100644
--- a/python/sglang/srt/model_executor/model_runner_kv_cache_mixin.py
+++ b/python/sglang/srt/model_executor/model_runner_kv_cache_mixin.py
@@ -145,6 +145,23 @@ class ModelRunnerKVCacheMixin:
         server_args = self.server_args
         assert config is not None
 
+        # reserve the memory for the intermediate mamba states used for spec dec
+        if not self.spec_algorithm.is_none():
+            assert server_args.speculative_num_draft_tokens is not None
+            assert server_args.max_running_requests is not None
+
+            max_running_requests = server_args.max_running_requests // (
+                self.dp_size if server_args.enable_dp_attention else 1
+            )
+            mamba_state_intermediate_size = (
+                config.mamba2_cache_params.mamba_cache_per_req
+                * max_running_requests
+                * server_args.speculative_num_draft_tokens
+            )
+            total_rest_memory = total_rest_memory - (
+                mamba_state_intermediate_size / (1 << 30)
+            )
+
         if (
             server_args.disable_radix_cache
             or server_args.max_mamba_cache_size is not None
@@ -160,19 +177,6 @@ class ModelRunnerKVCacheMixin:
             )
         else:
             assert config.mamba2_cache_params.mamba_cache_per_req > 0
-            # reserve the memory for the intermediate mamba states used for spec dec
-            if not self.spec_algorithm.is_none():
-                assert server_args.speculative_num_draft_tokens is not None
-                assert server_args.max_running_requests is not None
-
-                mamba_state_intermediate_size = (
-                    config.mamba2_cache_params.mamba_cache_per_req
-                    * server_args.max_running_requests
-                    * server_args.speculative_num_draft_tokens
-                )
-                total_rest_memory = total_rest_memory - (
-                    mamba_state_intermediate_size / (1 << 30)
-                )
 
             # allocate the memory based on the ratio between mamba state memory vs. full kv cache memory
             # solve the equations:
@@ -284,13 +288,11 @@ class ModelRunnerKVCacheMixin:
 
         if self.mambaish_config is not None:
             additional_ratio = 0
-            if (
-                self.server_args.enable_mamba_extra_buffer()
-                and not self.spec_algorithm.is_none()
-            ):
-                additional_ratio = MAMBA_CACHE_V2_ADDITIONAL_RATIO_NO_OVERLAP
-            else:
-                additional_ratio = MAMBA_CACHE_V2_ADDITIONAL_RATIO_OVERLAP
+            if self.server_args.enable_mamba_extra_buffer():
+                if not self.spec_algorithm.is_none():
+                    additional_ratio = MAMBA_CACHE_V2_ADDITIONAL_RATIO_NO_OVERLAP
+                else:
+                    additional_ratio = MAMBA_CACHE_V2_ADDITIONAL_RATIO_OVERLAP
             if self.server_args.disable_radix_cache:
                 ratio = 1
             else:
@@ -298,6 +300,14 @@ class ModelRunnerKVCacheMixin:
             max_num_reqs = min(
                 max_num_reqs, self.server_args.max_mamba_cache_size // ratio
             )
+            # for dp attention, we need control the max_num_reqs for speculative decoding mamba space
+            if (
+                not self.spec_algorithm.is_none()
+                and self.server_args.enable_dp_attention
+            ):
+                max_num_reqs = min(
+                    max_num_reqs, self.server_args.max_running_requests // self.dp_size
+                )
 
         if not self.spec_algorithm.is_none():
             if self.is_draft_worker: