diff --git a/fast_llm/functional/config.py b/fast_llm/functional/config.py
index 22f23174b..0b7b14ab1 100644
--- a/fast_llm/functional/config.py
+++ b/fast_llm/functional/config.py
@@ -15,7 +15,7 @@ class TritonConfig:
     MAX_BLOCK_SIZE_BYTES = 65536
 
 
-class MLPRecomputeLevel(str, enum.Enum):
+class MLPRecomputeLevel(enum.StrEnum):
     none = "none"
     activation = "activation"
     activation_and_input = "activation_and_input"
diff --git a/fast_llm/functional/triton/sparse_copy.py b/fast_llm/functional/triton/sparse_copy.py
index 258a2578b..7c803689c 100644
--- a/fast_llm/functional/triton/sparse_copy.py
+++ b/fast_llm/functional/triton/sparse_copy.py
@@ -11,10 +11,15 @@
 @dataclasses.dataclass()
 class SparseMap:
     sparse_rows: torch.Tensor
+    # The end row for each expert, including padding. `expert_ends[i] = expert_begins[i] + padded_tokens_per_expert[i]`
     expert_ends: torch.Tensor
+    # The end row for each expert, excluding padding. `expert_pad_begins[i] = expert_begins[i] + unpadded_tokens_per_expert[i]`
     expert_pad_begins: torch.Tensor
+    # The number of rows un the dense tensor, i.e., the number of tokens.
     num_rows_dense: int
+    # The number of sparse rows, including padding. `num_rows = expert_ends[-1]`
     num_rows: int
+    # The number of sparse rows, excluding padding. `num_rows_unpadded = num_rows_dense * num_experts_per_token`
     num_rows_unpadded: int
     num_experts: int
     num_experts_per_token: int
diff --git a/fast_llm/functional/triton/sparse_linear.py b/fast_llm/functional/triton/sparse_linear.py
index 9a0864944..ae46655ea 100644
--- a/fast_llm/functional/triton/sparse_linear.py
+++ b/fast_llm/functional/triton/sparse_linear.py
@@ -1,10 +1,12 @@
+import os
+
 import torch
 
 from fast_llm.functional.triton import TritonConfig, tl, tl_constexpr, triton, triton_autotune, triton_jit
 from fast_llm.functional.triton.sparse_copy import SparseMap
 from fast_llm.utils import Assert, div
 
-autotune_configs = [
+autotune_configs = (
     TritonConfig(
         {"block_size_row": 128, "block_size_col": 256, "block_size_inner": 64, "group_size_row": 8},
         num_stages=3,
@@ -45,7 +47,10 @@
         num_stages=5,
         num_warps=2,
     ),
-]
+)
+
+if os.environ.get("FAST_LLM_SKIP_TRITON_AUTOTUNE"):
+    autotune_configs = (autotune_configs[2],)
 
 
 @triton_autotune(
@@ -255,13 +260,13 @@ def output_sparse_matmul_kernel(
 def output_sparse_matmul(
     lhs: torch.Tensor,
     rhs: torch.Tensor,
-    sparse_map: SparseMap | None,
+    sparse_map: SparseMap | None = None,
     out: torch.Tensor | None = None,
     accumulate: bool = False,
 ) -> torch.Tensor:
     """
-    Output-sparse matrix multiplication with a sparse column dimension,
-    i.e., with a mapping row_index -> sparse_index (obtained from expert_ends).
+    Output-sparse matrix multiplication with a sparse column dimension
+    and a mapping row_index -> sparse_index (obtained from expert_ends).
     Ex.: MLP layer 1 forward (Y = X x W1^T), MLP layer 2 input grad (gY = gZ x W2).
     Formula: out[i, js] = sum_k(lhs[i, k] * rhs[k, jd]), where jd = js + col_sparse_dim * sparse_index[i]
       sparse_index[i] = sum(expert_ends <= i)
@@ -381,13 +386,13 @@ def input_inner_sparse_matmul_kernel(
 def input_inner_sparse_matmul(
     lhs: torch.Tensor,
     rhs: torch.Tensor,
-    sparse_map: SparseMap | None,
+    sparse_map: SparseMap | None = None,
     out: torch.Tensor | None = None,
     accumulate: bool = False,
 ) -> torch.Tensor:
     """
-    Left-input-sparse matrix multiplication with a sparse inner dimension,
-    i.e., with a mapping row_index -> sparse_index (obtained from expert_ends).
+    Left-input-sparse matrix multiplication with a sparse inner dimension
+    and a mapping row_index -> sparse_index (obtained from expert_ends).
     Ex.: MLP layer 2 forward (Z = Y x W2^T), MLP layer 1 input grad (gX = gY x W1).
     Formula: out[i, j] = sum_ks(lhs[i, ks] * rhs[kd, j]), where kd = ks + inner_sparse_dim * sparse_index[i]
       sparse_index[i] = sum(expert_ends <= i)
@@ -511,13 +516,13 @@ def input_row_sparse_matmul_kernel(
 def input_row_sparse_matmul(
     lhs: torch.Tensor,
     rhs: torch.Tensor,
-    sparse_map: SparseMap | None,
+    sparse_map: SparseMap | None = None,
     out: torch.Tensor | None = None,
     accumulate: bool = False,
 ) -> torch.Tensor:
     """
-    Left-input-sparse matrix multiplication with a sparse row dimension,
-    i.e., with a mapping inner_index -> sparse_index.
+    Left-input-sparse matrix multiplication with a sparse row dimension
+    and a mapping inner_index -> sparse_index.
     Ex.: MLP layer 1 weight grad (gW1 = gY^T x X), MLP layer 2 weight grad (gW2^T = Y^T x gZ).
     Formula: out[id, j] = sum_ks(lhs[is, ks] * rhs[ks, j]), where
       sparse_begin[sparse_index[id]] <= ks < sparse_end[sparse_index[id]],
diff --git a/fast_llm/models/ssm/model.py b/fast_llm/models/ssm/model.py
index 526d66c01..d6a2f7e1a 100644
--- a/fast_llm/models/ssm/model.py
+++ b/fast_llm/models/ssm/model.py
@@ -3,14 +3,13 @@
 
 from fast_llm.engine.base_model.base_model import Layer
 from fast_llm.engine.distributed.config import DistributedConfig
-from fast_llm.engine.multi_stage.fast_llm_model import FastLLMModel
 from fast_llm.layers.language_model.embedding import LanguageModelEmbedding
 from fast_llm.layers.language_model.head import LanguageModelHead
 from fast_llm.layers.ssm.discrete_mamba2 import DiscreteMamba2
 from fast_llm.layers.ssm.llamba_block import LlambaBlock
 from fast_llm.layers.ssm.mamba_layer import MambaLayer
 from fast_llm.layers.transformer.transformer import TransformerLayer
-from fast_llm.models.gpt.model import GPTBaseModel
+from fast_llm.models.gpt.model import GPTBaseModel, GPTModel
 from fast_llm.models.ssm.config import HybridSSMBaseModelConfig, HybridSSMModelConfig, SSMBlockType
 
 logger = logging.getLogger(__name__)
@@ -135,7 +134,7 @@ def get_layers(self) -> list[Layer]:
         return layers
 
 
-class HybridSSMModel[ConfigType: HybridSSMModelConfig](FastLLMModel[ConfigType]):
+class HybridSSMModel[ConfigType: HybridSSMModelConfig](GPTModel[ConfigType]):
     """
     A hybrid model that combines Transformer and SSM blocks.
     """
diff --git a/setup.cfg b/setup.cfg
index b3b1df036..b1e44e814 100644
--- a/setup.cfg
+++ b/setup.cfg
@@ -24,6 +24,8 @@ CORE =
     safetensors>=0.5.3
     # Update the base image (version fixed to ensure there is a wheel for the base image), may need --no-build-isolation
     flash-attn==2.7.3
+    # Dropless MLP is broken with triton 3.2.0, 3.3.0 and 3.3.1. TODO: Remove once a working triton version is released.
+    triton==3.1.0
 
 
 # Small packages required for some optional features and tools.
@@ -57,7 +59,7 @@ DEV =
     pytest-xdist>=3.7.0
     # Somehow needed for Megatron to work with base image 24.11
     setuptools>=80.9.0
-    # dependency manager needs it.
+    # Dependency manager needs colorama to show colors.
     colorama>=0.4.6
 
 # Required for building the documentation
diff --git a/tests/conftest.py b/tests/conftest.py
index 0d25fc5aa..11757176e 100644
--- a/tests/conftest.py
+++ b/tests/conftest.py
@@ -113,6 +113,9 @@ def pytest_configure(config):
         rendezvous_port=TORCHRUN_DEFAULT_PORT + 2 * worker_id + 1,
     )
 
+    # Skip slow autotune for tests. The default config has the highest block size, so this shouldn't hide any bug.
+    os.environ["FAST_LLM_SKIP_TRITON_AUTOTUNE"] = "TRUE"
+
 
 @pytest.hookimpl(trylast=True)
 def pytest_collection_modifyitems(config, items: list[pytest.Function]):
diff --git a/tests/functional/__init__.py b/tests/functional/__init__.py
new file mode 100644
index 000000000..e69de29bb
diff --git a/tests/test_functional.py b/tests/functional/test_functional.py
similarity index 98%
rename from tests/test_functional.py
rename to tests/functional/test_functional.py
index 9211259c2..3ddd5d4fe 100644
--- a/tests/test_functional.py
+++ b/tests/functional/test_functional.py
@@ -224,8 +224,6 @@ def test_mlp_recomputation(gated, activation_type):
 @pytest.mark.slow
 @requires_cuda
 def test_dropless_mlp():
-    # TODO: Fix dropless MOE
-    pytest.fail("Test fails, aborting to avoid breaking cuda", False)
     num_experts = 4
     experts_per_token = 4
     tokens = 256
@@ -273,7 +271,7 @@ def test_dropless_mlp():
     sparse_map = get_sparse_map(top_experts, num_experts)
 
     for i, recompute_level in enumerate(MLPRecomputeLevel):
-        print(recompute_level.value)  # noqa
+        print("recompute_level", recompute_level)  # noqa
         input_.grad = None
         scores.grad = None
         for param in params:
diff --git a/tests/functional/test_sparse_matmul.py b/tests/functional/test_sparse_matmul.py
new file mode 100644
index 000000000..899dad967
--- /dev/null
+++ b/tests/functional/test_sparse_matmul.py
@@ -0,0 +1,154 @@
+import dataclasses
+import functools
+
+import pytest
+import torch
+
+from fast_llm.functional.triton.sparse_copy import SparseMap
+from fast_llm.functional.triton.sparse_linear import (
+    dense_matmul,
+    input_inner_sparse_matmul,
+    input_row_sparse_matmul,
+    output_sparse_matmul,
+)
+from fast_llm.utils import Assert
+from tests.utils.utils import requires_cuda
+
+
+@dataclasses.dataclass
+class _SparseTestData:
+    dense_dim: int
+    sparse_dim: int
+    expert_ends: tuple[int, ...]
+    tokens_per_expert: tuple[int, ...]
+    std: float = 0.125
+
+    @functools.cached_property
+    def expert_begins(self) -> tuple[int, ...]:
+        return (0,) + self.expert_ends[:-1]
+
+    @functools.cached_property
+    def expert_pad_begins(self) -> tuple[int, ...]:
+        return tuple(
+            expert_begin + expert_tokens
+            for expert_begin, expert_tokens in zip(self.expert_begins, self.tokens_per_expert, strict=True)
+        )
+
+    @functools.cached_property
+    def token_dim(self) -> int:
+        return self.expert_ends[-1]
+
+    @property
+    def sparse_dim_expanded(self) -> int:
+        return self.sparse_dim * self.num_experts
+
+    @functools.cached_property
+    def num_experts(self) -> int:
+        return len(self.expert_begins)
+
+    @functools.cached_property
+    def sparse_map(self) -> SparseMap:
+        return SparseMap(
+            num_experts=self.num_experts,
+            expert_ends=torch.tensor(self.expert_ends, device="cuda"),
+            expert_pad_begins=torch.tensor(self.expert_pad_begins, device="cuda"),
+            num_rows=self.expert_ends[-1],
+            # Not needed
+            sparse_rows=None,
+            num_rows_dense=None,
+            num_rows_unpadded=None,
+            num_experts_per_token=None,
+        )
+
+    def normal(self, dim_0: int, dim_1: int) -> torch.Tensor:
+        return torch.normal(0, self.std, (dim_0, dim_1), device="cuda")
+
+
+_SPARSE_TEST_DATAS = (
+    _SparseTestData(
+        dense_dim=384,
+        sparse_dim=256,
+        expert_ends=(128, 384, 512),
+        tokens_per_expert=(78, 256, 54),
+    ),
+    _SparseTestData(
+        dense_dim=256,
+        sparse_dim=512,
+        expert_ends=(128, 256, 256, 384),
+        tokens_per_expert=(52, 125, 0, 97),
+    ),
+)
+
+
+@requires_cuda
+@pytest.mark.slow
+@pytest.mark.parametrize("sparse_test_data", _SPARSE_TEST_DATAS)
+def test_dense_matmul(sparse_test_data):
+    lhs = sparse_test_data.normal(sparse_test_data.token_dim, sparse_test_data.dense_dim)
+    rhs = sparse_test_data.normal(sparse_test_data.dense_dim, sparse_test_data.sparse_dim)
+
+    output = dense_matmul(lhs, rhs)
+    output_ref = torch.matmul(lhs, rhs)
+    Assert.rms_close(output, output_ref, 1e-3)
+
+
+@requires_cuda
+@pytest.mark.slow
+@pytest.mark.parametrize("sparse_test_data", _SPARSE_TEST_DATAS)
+def test_output_sparse_matmul(sparse_test_data):
+    lhs = sparse_test_data.normal(sparse_test_data.token_dim, sparse_test_data.dense_dim)
+    rhs = sparse_test_data.normal(sparse_test_data.dense_dim, sparse_test_data.sparse_dim_expanded)
+
+    # Randomly initialize the output to ensure padded values have no effect.
+    out = sparse_test_data.normal(sparse_test_data.token_dim, sparse_test_data.sparse_dim)
+    output = output_sparse_matmul(lhs, rhs, sparse_test_data.sparse_map, out)
+
+    output_ref = torch.zeros_like(output)
+    for i in range(sparse_test_data.num_experts):
+        # Padded tokens are treated like regular ones.
+        output_ref[sparse_test_data.expert_begins[i] : sparse_test_data.expert_ends[i]] = torch.matmul(
+            lhs[sparse_test_data.expert_begins[i] : sparse_test_data.expert_ends[i]],
+            rhs[:, i * sparse_test_data.sparse_dim : (i + 1) * sparse_test_data.sparse_dim],
+        )
+
+    Assert.rms_close(output, output_ref, 1e-3)
+
+
+@requires_cuda
+@pytest.mark.slow
+@pytest.mark.parametrize("sparse_test_data", _SPARSE_TEST_DATAS)
+def test_input_inner_sparse_matmul(sparse_test_data):
+    lhs = sparse_test_data.normal(sparse_test_data.token_dim, sparse_test_data.sparse_dim)
+    rhs = sparse_test_data.normal(sparse_test_data.sparse_dim_expanded, sparse_test_data.dense_dim)
+
+    output = input_inner_sparse_matmul(lhs, rhs, sparse_test_data.sparse_map)
+
+    output_ref = torch.zeros_like(output)
+    for i in range(sparse_test_data.num_experts):
+        # Padded tokens are treated like regular ones.
+        output_ref[sparse_test_data.expert_begins[i] : sparse_test_data.expert_ends[i]] = torch.matmul(
+            lhs[sparse_test_data.expert_begins[i] : sparse_test_data.expert_ends[i]],
+            rhs[i * sparse_test_data.sparse_dim : (i + 1) * sparse_test_data.sparse_dim],
+        )
+
+    Assert.rms_close(output, output_ref, 1e-3)
+
+
+@requires_cuda
+@pytest.mark.slow
+@pytest.mark.parametrize("sparse_test_data", _SPARSE_TEST_DATAS)
+def test_input_row_sparse_matmul(sparse_test_data):
+    lhs = sparse_test_data.normal(sparse_test_data.sparse_dim, sparse_test_data.token_dim)
+    rhs = sparse_test_data.normal(sparse_test_data.token_dim, sparse_test_data.dense_dim)
+
+    output = input_row_sparse_matmul(lhs, rhs, sparse_test_data.sparse_map)
+
+    output_ref = torch.zeros_like(output)
+    for i in range(sparse_test_data.num_experts):
+        # Padded tokens are excluded from the sum.
+        output_ref[i * sparse_test_data.sparse_dim : (i + 1) * sparse_test_data.sparse_dim] = torch.matmul(
+            lhs[:, sparse_test_data.expert_begins[i] : sparse_test_data.expert_pad_begins[i]],
+            rhs[sparse_test_data.expert_begins[i] : sparse_test_data.expert_pad_begins[i]],
+        )
+
+    Assert.rms_close(output, output_ref, 1e-3)
diff --git a/tests/test_triton_kernels.py b/tests/functional/test_triton_kernels.py
similarity index 100%
rename from tests/test_triton_kernels.py
rename to tests/functional/test_triton_kernels.py
diff --git a/tests/models/test_checkpoint.py b/tests/models/test_checkpoint.py
index 39fd0840e..aff7d991f 100644
--- a/tests/models/test_checkpoint.py
+++ b/tests/models/test_checkpoint.py
@@ -30,7 +30,7 @@ def test_checkpoint_and_eval(run_test_script_for_all_models, model_testing_confi
         + [
             "training.checkpoint.interval=1",
             "training.evaluators.validation.interval=2",
-            "training.evaluators.validation.evaluators.iterations=1",
+            "training.evaluators.validation.evaluator.iterations=1",
         ],
     )
 
@@ -63,7 +63,7 @@ def test_resume(run_test_script_for_all_models):
         [
             "training.checkpoint.interval=1",
             "training.evaluators.validation.interval=2",
-            "training.evaluators.validation.evaluators.iterations=1",
+            "training.evaluators.validation.evaluator.iterations=1",
         ],
         compare=f"test_checkpoint_and_eval",
         prepare_fn=_prepare_resume_fn,
@@ -79,7 +79,7 @@ def test_resume_frozen(run_test_script_for_all_models):
         [
             "training.checkpoint.interval=1",
             "training.evaluators.validation.interval=2",
-            "training.evaluators.validation.evaluators.iterations=1",
+            "training.evaluators.validation.evaluator.iterations=1",
             "model.base_model.transformer.mlp_lr_scale=0.",
         ],
         compare="test_checkpoint_and_eval",
@@ -442,7 +442,12 @@ def test_run_converted_model(model_testing_config, convert_paths):
     )
     errors = []
     compare = CompareConfig()
-    model_as_hf = transformers.AutoModel.from_pretrained(
+    auto_model = (
+        transformers.AutoModel
+        if model_testing_config.name in ("diffusion_llama", "dream")
+        else transformers.AutoModelForCausalLM
+    )
+    model_as_hf = auto_model.from_pretrained(
         convert_paths["huggingface_0"], trust_remote_code=model_testing_config.checkpoint_format.trust_remote_code
     ).cuda()
     for name, model in zip(