--- a/vllm/v1/core/kv_cache_utils.py
+++ b/vllm/v1/core/kv_cache_utils.py
@@ -1395,10 +1395,34 @@
         return kv_cache_spec
 
     max_page_size = max(page_sizes)
+    # GLM-5.3-Flash + a draft model: the sparse indexer k_cache page is
+    # tokens_per_state x the MLA page (same per-token bytes), and MLA layers
+    # cannot be PADDED to an arbitrary page size (sparse MLA indexes the cache
+    # in whole token rows) -- but they CAN grow their block size when the max
+    # page is an exact multiple of the MLA page. Bump the max page to a
+    # multiple of every MLA-family page so all of them take the divisible
+    # block-growth branch below instead of the padding refusal, while the
+    # draft and mamba layers simply pad to the (slightly larger) page.
+    mla_pages = {
+        spec.page_size_bytes
+        for spec in kv_cache_spec.values()
+        if isinstance(spec, MLAAttentionSpec)
+    }
+    if mla_pages:
+        mla_common = math.lcm(*mla_pages)
+        max_page_size = -(-max_page_size // mla_common) * mla_common
     new_kv_cache_spec = {}
     for layer_name, layer_spec in kv_cache_spec.items():
         if layer_spec.page_size_bytes == max_page_size:
             new_kv_cache_spec[layer_name] = layer_spec
+        elif isinstance(layer_spec, KpoolTailSpec):
+            # The kpool tail kernel pins the tail block to the kpool size
+            # (tail_kv_cache.view(...) must be [blocks, 2, index_kpool,
+            # head_dim]); growing block_size breaks that contract. Pad the
+            # physical page instead -- the tail is its own group and the pad
+            # wastes bytes only.
+            new_spec = replace(layer_spec, page_size_padded=max_page_size)
+            new_kv_cache_spec[layer_name] = new_spec
         elif isinstance(layer_spec, MambaSpec):
             # MambaSpec's page size is determined by its state shapes and does
             # not scale with block_size, so pad the page instead. This is the