[Bugfix] Restore overridden HF config fields and support index_skip_topk_offset for DSA topk sharing (#27114)

python/sglang/srt/batch_overlap/two_batch_overlap.py

@@ -701,6 +701,7 @@ class TboForwardBatchPreparer:
             "split_index",  # for split prefill
             "orig_seq_lens",  # only used by qwen-1m, thus not care
             "return_pooled_hidden_states",
+            "reuse_mtp_topk_indices",  # forward-level flag, inherited by both child batches
         ]:
             output_dict[key] = getattr(batch, key)
 

python/sglang/srt/model_executor/forward_batch_info.py

@@ -385,6 +385,10 @@ class ForwardBatch(ForwardBatchDeepSeekMHAMixin):
     # For hidden states before normal
     return_hidden_states_before_norm: bool = False
 
+    # For NSA/DSA topk_indices reuse across forward calls (e.g., EAGLE draft)
+    topk_indices: Optional[torch.Tensor] = None
+    reuse_mtp_topk_indices: Optional[bool] = False
+
     # === Forward-derived (built in init_new on the forward stream; FB-owned) ===
     # Position information
     positions: torch.Tensor = None

python/sglang/srt/models/deepseek_common/attention_forward_methods/forward_mla.py

@@ -245,7 +245,15 @@ class DeepseekMLAForwardMixin:
                     q = self.q_b_proj(q)[0].view(
                         -1, self.num_local_heads, self.qk_head_dim
                     )
-                if not self.skip_topk or prev_topk_indices is None:
+                # skip_topk (shared) layers carry no indexer weights in the
+                # checkpoint, so they must reuse the carried topk and never run
+                # the indexer. Do NOT widen this to `or prev_topk_indices is
+                # None` (the upstream gate): that recomputes with an
+                # uninitialized indexer whenever cross-layer propagation is
+                # unavailable (e.g. the TBO op path drops topk_indices),
+                # reintroducing the >index_topk garbling. The is_nextn clause is
+                # the sole intentional fallback (layer 78 has its own weights).
+                if not self.skip_topk or (self.is_nextn and prev_topk_indices is None):
                     topk_indices = self.indexer(
                         x=hidden_states,
                         q_lora=q_lora,
@@ -264,7 +272,12 @@ class DeepseekMLAForwardMixin:
                 k_nope = k_nope.unsqueeze(1)
                 q = self.q_b_proj(q)[0].view(-1, self.num_local_heads, self.qk_head_dim)
                 if q_lora is not None:
-                    if not self.skip_topk or prev_topk_indices is None:
+                    # See the skip_topk note above: shared layers have no
+                    # indexer weights, so this gate must not fall back to
+                    # computing when prev_topk_indices is None.
+                    if not self.skip_topk or (
+                        self.is_nextn and prev_topk_indices is None
+                    ):
                         topk_indices = self.indexer(
                             x=hidden_states,
                             q_lora=q_lora,

python/sglang/srt/models/deepseek_nextn.py

@@ -230,7 +230,14 @@ class DeepseekModelNextN(nn.Module):
                     forward_batch,
                     residual,
                     zero_allocator,
+                    prev_topk_indices=(
+                        forward_batch.topk_indices
+                        if forward_batch.reuse_mtp_topk_indices
+                        else None
+                    ),
                 )
+                if forward_batch.reuse_mtp_topk_indices:
+                    forward_batch.topk_indices = topk_indices
 
             if not forward_batch.forward_mode.is_idle():
                 if residual is not None:

python/sglang/srt/models/deepseek_v2.py

@@ -1469,6 +1469,7 @@ class DeepseekV2AttentionMLA(
         self.q_lora_rank = q_lora_rank
         self.kv_lora_rank = kv_lora_rank
         self.quant_config = quant_config
+        self.is_nextn = is_nextn
         attn_tp_rank = get_attention_tp_rank()
         attn_tp_size = get_attention_tp_size()
         self.use_dsa = is_deepseek_dsa(config)
@@ -1556,12 +1557,33 @@ class DeepseekV2AttentionMLA(
             # skip_topk: when True, this layer will skip computation and reuse previous layer's topk indices.
             # next_skip_topk: when True, the next layer will skip computation and reuse this layer's topk indices.
             if is_nextn:
-                self.skip_topk = False
-                self.next_skip_topk = False
+                self.skip_topk = True
+                self.next_skip_topk = True
             else:
                 self.index_topk_freq = getattr(config, "index_topk_freq", 1)
                 self.index_topk_pattern = getattr(config, "index_topk_pattern", None)
-                if self.index_topk_pattern is None:
+                self.index_skip_topk_offset = getattr(
+                    config, "index_skip_topk_offset", None
+                )
+                if (
+                    self.index_topk_pattern is None
+                    and self.index_skip_topk_offset is not None
+                ):
+                    assert self.index_skip_topk_offset > 0, (
+                        "index_skip_topk_offset must be positive; offset <= 0 "
+                        "marks layer 0 as skip_topk with no prior topk to reuse"
+                    )
+                    self.skip_topk = (
+                        max(layer_id - self.index_skip_topk_offset + 1, 0)
+                        % self.index_topk_freq
+                        != 0
+                    )
+                    self.next_skip_topk = (
+                        max(layer_id - self.index_skip_topk_offset + 2, 0)
+                        % self.index_topk_freq
+                        != 0
+                    )
+                elif self.index_topk_pattern is None:
                     self.skip_topk = max(layer_id - 1, 0) % self.index_topk_freq != 0
                     self.next_skip_topk = layer_id % self.index_topk_freq != 0
                 else:

python/sglang/srt/server_args.py

@@ -1851,6 +1851,20 @@ class ServerArgs:
                     self.attention_backend = "dsa"
                     logger.info("Use dsa attention backend for DeepSeek with DSA.")
 
+                index_topk_freq = getattr(hf_config, "index_topk_freq", 1)
+                index_topk_pattern = getattr(hf_config, "index_topk_pattern", None)
+                if self.enable_two_batch_overlap and (
+                    index_topk_freq > 1
+                    or (index_topk_pattern is not None and "S" in index_topk_pattern)
+                ):
+                    raise ValueError(
+                        "--enable-two-batch-overlap is not supported with DSA "
+                        "index-topk sharing (index_topk_freq > 1 or an "
+                        "index_topk_pattern containing shared layers): the TBO op "
+                        "path does not propagate topk indices across layers, so "
+                        "shared layers would run sparse attention without indices."
+                    )
+
                 if not is_npu() and not is_xpu():  # CUDA or ROCm GPU
                     if self.enable_dsa_prefill_context_parallel:
                         logger.warning(

python/sglang/srt/speculative/eagle_worker.py

@@ -897,6 +897,17 @@ class EAGLEWorker(TpModelWorker):
 
         # Forward multiple steps
         scores = None
+        # Reuse NSA/DSA topk_indices from the first draft forward step for
+        # subsequent steps, analogous to skip_topk in deepseek_v2.py layers.
+        # Only safe with topk == 1: select_top_k_tokens reorders candidate rows
+        # each step, which would desync the cached indices from their rows.
+        index_share_for_mtp_iteration = (
+            getattr(self.model_config.hf_config, "index_share_for_mtp_iteration", False)
+            and self.topk == 1
+        )
+        if index_share_for_mtp_iteration:
+            forward_batch.reuse_mtp_topk_indices = True
+            forward_batch.topk_indices = None
         for i in range(self.speculative_num_steps):
             input_ids, hidden_states, scores, tree_info = select_top_k_tokens(
                 i, topk_p, topk_index, hidden_states, scores, self.topk
@@ -949,6 +960,9 @@ class EAGLEWorker(TpModelWorker):
             maybe_detect_inf(hidden_states, f"draft_forward step {i}: hidden_states")
             forward_batch.positions.add_(1)
 
+        if index_share_for_mtp_iteration:
+            forward_batch.topk_indices = None
+            forward_batch.reuse_mtp_topk_indices = False
         parent_list, top_scores_index, draft_tokens = organize_draft_results(
             score_list, token_list, parents_list, self.speculative_num_draft_tokens
         )

python/sglang/srt/utils/hf_transformers/config.py

@@ -67,6 +67,26 @@ class HfModelConfigParser(ModelConfigParserBase):
             **kwargs,
         )
 
+        if (
+            config.architectures is not None
+            and config.architectures[0] == "GlmMoeDsaForCausalLM"
+        ):
+            # GlmMoeDsaConfig drops/clobbers raw checkpoint fields the DSA path
+            # needs, so re-read them from config.json and restore. Fixed upstream
+            # by https://github.com/huggingface/transformers/pull/46338; remove
+            # this block once SGLang requires transformers >= 5.10.
+            from transformers import PretrainedConfig
+
+            raw_config, _ = PretrainedConfig.get_config_dict(model, revision=revision)
+            for key in (
+                "qk_rope_head_dim",
+                "index_topk_freq",
+            ):
+                if key in raw_config:
+                    setattr(config, key, raw_config[key])
+            if hasattr(config, "qk_head_dim") and hasattr(config, "qk_nope_head_dim"):
+                config.qk_head_dim = config.qk_nope_head_dim + config.qk_rope_head_dim
+
         if (
             config.architectures is not None
             and config.architectures[0] == "Phi4MMForCausalLM"