diff --git a/src/llama-graph.cpp b/src/llama-graph.cpp
index 7309705dc..a49134e74 100644
--- a/src/llama-graph.cpp
+++ b/src/llama-graph.cpp
@@ -634,7 +634,10 @@ bool llm_graph_input_attn_kv_msa::can_reuse(const llm_graph_params & params) {
 void llm_graph_input_attn_k_dsa::set_input(const llama_ubatch * ubatch) {
     mctx->get_mla()->set_input_k_idxs(self_k_idxs_mla, ubatch);
 
-    mctx->get_mla()->set_input_kq_mask(self_kq_mask_mla, ubatch, cparams.causal_attn);
+    // leave unallocated when the top-k layers use the indexer mask
+    if (self_kq_mask_mla->buffer) {
+        mctx->get_mla()->set_input_kq_mask(self_kq_mask_mla, ubatch, cparams.causal_attn);
+    }
 
     mctx->get_lid()->set_input_k_idxs(self_k_idxs_lid, ubatch);
 
@@ -1218,7 +1221,10 @@ bool llm_graph_input_mem_hybrid::can_reuse(const llm_graph_params & params) {
 void llm_graph_input_mem_hybrid_k::set_input(const llama_ubatch * ubatch) {
     mctx->get_attn()->set_input_k_idxs(inp_attn->self_k_idxs, ubatch);
 
-    mctx->get_attn()->set_input_kq_mask(inp_attn->self_kq_mask, ubatch, cparams.causal_attn);
+    // leave the mask unallocated if all attention layers have their own (e.g. glm5-next DSA)
+    if (inp_attn->self_kq_mask->buffer) {
+        mctx->get_attn()->set_input_kq_mask(inp_attn->self_kq_mask, ubatch, cparams.causal_attn);
+    }
 
     const int64_t n_rs = mctx->get_recr()->get_n_rs();
 
@@ -3441,7 +3447,12 @@ ggml_tensor * llm_graph_context::build_attn(
         ggml_build_forward_expand(gf, mctx_cur->cpy_k(ctx0, k_cur, k_idxs, il));
     }
 
-    const auto & kq_mask = inp->get_kq_mask_mla();
+    // top_k indexes the cells, and the indexer mask of the same type is built the same way
+    // let's use it, so when no other layer reads the MLA mask is not allocated
+    ggml_tensor * kq_mask = inp->get_kq_mask_mla();
+    if (inp->get_kq_mask_lid()->type == kq_mask->type) {
+        kq_mask = inp->get_kq_mask_lid();
+    }
 
     ggml_tensor * kq_mask_top_k = nullptr;
     if (cparams.fused_top_k_mask) {
diff --git a/src/models/glm5-next.cpp b/src/models/glm5-next.cpp
index d1e9b503d..46019d6aa 100644
--- a/src/models/glm5-next.cpp
+++ b/src/models/glm5-next.cpp
@@ -971,12 +971,14 @@ ggml_tensor * llama_model_glm5_next::graph::build_kpool_select(
         const int64_t n_top_pool = std::min<int64_t>(n_pool, hparams.indexer_top_k / kpool);
         ggml_tensor * top_k = ggml_top_k(ctx0, score, n_top_pool); // [n_top_pool, n_tokens], UNORDERED
 
-        // keep the kq_mask cells of the live picked pools and the tail, -inf elsewhere
+        // keep the cells of the live picked pools and the tail, -inf elsewhere
+        // all retained cells are in the token's sequence, so the kq_mask is not needed
         if (cparams.fused_top_k_mask) {
             ggml_tensor * tail = hparams.indexer_kpool_select_tail ? inp_kpool->tail_idxs : nullptr;
             GGML_ASSERT(kpool*n_top_pool + (tail ? tail->ne[0] : 0) == (int64_t) inp_kpool->n_sel);
 
-            ggml_tensor * sel = build_fused_top_k_mask(kq_mask, top_k, score, inp_kpool->pool_idxs, tail, nullptr, il);
+            ggml_tensor * keep = ggml_fill(ctx0, ggml_new_tensor_1d(ctx0, kq_mask->type, n_kv), 0.0f);
+            ggml_tensor * sel  = build_fused_top_k_mask(kq_mask, top_k, score, inp_kpool->pool_idxs, tail, keep, il);
             cb(sel, "indexer_sel", il);
 
             return sel;
@@ -1032,7 +1034,7 @@ ggml_tensor * llama_model_glm5_next::graph::build_kpool_select(
     const size_t row = sel->nb[2];
     sel = ggml_view_4d(ctx0, sel, n_kv, kq_mask->ne[1], kq_mask->ne[2], kq_mask->ne[3],
             row, row*kq_mask->ne[1], row*kq_mask->ne[1]*kq_mask->ne[2], 0);
-    sel = ggml_add(ctx0, sel, kq_mask);
+    sel = ggml_cont(ctx0, sel);
     cb(sel, "indexer_sel", il);
 
     return sel;
@@ -1086,7 +1088,8 @@ llama_model_glm5_next::graph::build_dsa_layer(
     ggml_build_forward_expand(gf, kv_cmpr);
     ggml_build_forward_expand(gf, mctx_mla->cpy_k(ctx0, kv_cmpr, inp_attn->get_k_idxs(), il));
 
-    // The scatter selection already includes the causal mask, and it comes in the mask layout
+    // the selection replaces the kq_mask and has the same shape
+    // with no layers reading it, the kq_mask isn't allocated
     GGML_ASSERT(ggml_are_same_shape(sel, kq_mask));
     cb(sel, "kq_mask_dsa", il);