# Sparse bmm cause CUDA misaligned address error

**URL:** <https://discuss.pytorch.org/t/sparse-bmm-cause-cuda-misaligned-address-error/223661>\
**Category:** Memory Format\
**Created:** [October 21, 2025, 1:14pm UTC](https://discuss.pytorch.org/t/sparse-bmm-cause-cuda-misaligned-address-error/223661 "2025-10-21T13:14:00Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![gimal](https://discuss.pytorch.org/user_avatar/discuss.pytorch.org/gimal/32/78480_2.png) [@gimal](https://discuss.pytorch.org/u/gimal)\
**Post date:** [October 21, 2025, 1:14pm UTC](https://discuss.pytorch.org/t/sparse-bmm-cause-cuda-misaligned-address-error/223661/1 "2025-10-21T13:14:00Z")

</div>

Hi everyone,  
I’m new to pytorch, cuda and sparse memory format. I’m doing computation on batch sparse tensor, in this code:

```auto
import torch
from torch import Tensor

SEED = 42
# torch.random.manual_seed(SEED)

def generate_random_dataset(
min_num_categorical: int,
max_num_categorical: int,
min_groups: int,
max_groups: int,
min_rows: int,
max_rows: int,
shuffle_rows: bool,
dtype=torch.float64,
) → torch.Tensor:
def randn_scalar(low=0.0, high=1.0):
return torch.normal(low, high, size=())

def randint_scalar(low, high):
    return torch.randint(low, high, size=()).item()

# --- Covariance Matrix Setup (Numerical Columns X and Y) ---
cov_scalar = randn_scalar()
number_of_groups = randint_scalar(min_groups, max_groups)

means = torch.tensor(
    [
        randint_scalar(-5, 6),
        randint_scalar(-5, 6),
    ],
    dtype=dtype,
)
var_X = randn_scalar() * randint_scalar(1, 6)
var_Y = randn_scalar() * randint_scalar(1, 6)

# Create and "square" the matrix to ensure it's positive semi-definite
A = torch.tensor([[var_X, cov_scalar], [cov_scalar, var_Y]], dtype=dtype)
cov_matrix = A.T @ A

groups = []

for shift in range(number_of_groups):
    group_size = randint_scalar(min_rows, max_rows)
    group_xy = (
        torch.distributions.MultivariateNormal(means, cov_matrix).sample(
            (group_size,)
        )
        + shift * 0.5
    )

    # Create the Kth column (key/group ID)
    group_k = torch.full((group_size, 1), fill_value=shift, dtype=dtype)

    # Concatenate K, X, Y: [K | X | Y]
    group = torch.hstack([group_k, group_xy])
    groups.append(group)

data = torch.cat(groups, dim=0)

if max_num_categorical >= min_num_categorical > 0:
    N = data.shape[0]

    # randomly define how many categorical columns we will append
    # this number consider the basic one created above
    num_categorical = (
        randint_scalar(min_num_categorical, max_num_categorical + 1) - 1
    )

    # Generate random number of categories for each column
    # ensuring they're sorted in ascending order
    num_categories_list = sorted(
        [randint_scalar(2, number_of_groups) for _ in range(num_categorical)]
    )

    # Ensure last categorical column has <= distinct values than K column
    num_categories_list[-1] = int(
        min(
            torch.tensor(num_categories_list[-1]),
            torch.tensor(number_of_groups),
        ).item()
    )

    categorical_cols = []

    # Get the categorical data from a normal distribution
    # combined with a multinomial one
    for num_categories in num_categories_list:
        y = (
            torch.distributions.Normal(
                loc=torch.tensor([10.0]), scale=torch.tensor([5.0])
            )
            .sample((num_categories,))
            .reshape((1, -1))
        )
        y = y * torch.sign(y)
        y, _ = torch.sort(y)
        y = y / torch.norm(y)

        d = torch.multinomial(y, num_samples=N, replacement=True).reshape((-1, 1))
        categorical_cols.append(d)

    # Prepend categorical columns to data
    categorical_data = torch.hstack(categorical_cols)
    categorical_data = categorical_data.to(dtype=dtype)
    data = torch.hstack([categorical_data, data])

if shuffle_rows:
    indices = torch.randperm(data.shape[0])
    data = data[indices]
return data

def t_create_batch_index_matrix_sparse(D: Tensor, dtype=torch.float64) → Tensor:
# B: number of categorical columns
# N: number of records
# K: number of groups (max. number of unique elements among all categorical columns)
N, B = D.shape
K = D.unique(sorted=False).shape\[0\]

batch_idx = torch.arange(B, device=D.device).repeat_interleave(N)
row_idx = torch.arange(N, device=D.device).repeat(B)
column_idx = D.T.flatten()

indices = torch.stack([batch_idx, row_idx, column_idx])
values = torch.ones(B * N, device=D.device)
size = torch.Size([B, N, K])

G = torch.sparse_coo_tensor(
    indices=indices, values=values, size=size, dtype=dtype, device=D.device
).coalesce()

return G

def proc_batch_matrix_sparse(G: Tensor, X: Tensor, Y: Tensor) → Tensor:
B, N, K = G.shape

Xb = X.unsqueeze(0).expand(B, -1, -1).transpose(1, 2)
Yb = Y.unsqueeze(0).expand(B, -1, -1).transpose(1, 2)

Gt = G.transpose(1, 2)
GtX = torch.bmm(Gt, Xb)
return GtX.to("cpu")

if name == “main”:
DTYPE = torch.float64
GPU = True
NUMBER_OF_TESTS = 10

MIN_NUM_CATEGORICAL, MAX_NUM_CATEGORICAL = 50, 50
MIN_GROUPS, MAX_GROUPS = 10, 100
MIN_GROUP_ROWS, MAX_GROUP_ROWS = 50, 100

device = "cuda" if GPU and torch.cuda.is_available() else "cpu"

for i in range(NUMBER_OF_TESTS):
    print(f" Run {i} ".center(100, "="))
    data = generate_random_dataset(
        MIN_NUM_CATEGORICAL,
        MAX_NUM_CATEGORICAL,
        MIN_GROUPS,
        MAX_GROUPS,
        MIN_GROUP_ROWS,
        MAX_GROUP_ROWS,
        shuffle_rows=True,
        dtype=DTYPE,
    ).to(device)

    D = data[:, :-2] # batch of "categorical" columns [NxB]
    X = data[:, -2].reshape((1, -1))
    Y = data[:, -1].reshape((1, -1))

    G = t_create_batch_index_matrix_sparse(D, dtype=DTYPE)
    proc_batch_matrix_sparse(G, X, Y)

```

I create a random dataset (`generate_random_dataset`), take the last two columns as X and Y and the others are transformed into a sparse batch coo tensor of one hot encoded matrices. (`create_batch_matrix_index_sparse`) and pass these data to actual computation (`proc_batch_matrix_sparse`).

I encounter this error:

`torch.AcceleratorError: CUDA error: misaligned address`  
`Search for cudaErrorMisalignedAddress' in https://docs.nvidia.com/cuda/cuda-runtime-api/group __CUDART__ TYPES.html for more information. Compile with TORCH_USE_CUDA_DSA to enable device-side assertions.`

when computing batch matrix-matrix in `proc_batch_matrix_sparse`.  
I’ve checked the torch.sparse doc, and both Gt and Xb should satisfy the desired shapes and layouts. The error doesn’t occur at every run, and I have not detected specific conditions that may cause it, except that it happens more often with higher number of dataset rows. Moving G to dense seems to solve, but this is not desired (and feasible) for large inputs.

### Spec

I’ve ran tests with these two systems:

- GeForce RTX 4090, CUDA 12.2, Driver 535.104.05, torch 2.9;
- Tesla T4, CUDA 13.0, Driver 580.95.05, torch 2.9.

### Update

Running this on single matrices in the batch (with torch.sparse.mm) and then stacking results works fine, but a loop on batch index is required;  
Output of compute-sanitizer is a long list of:

```auto
========= Invalid __global__ read of size 16 bytes
========= at void cusparse::coomv_kernel<(bool)0, int, double, double, double, double>(cusparse::KernelCoeffs<T6>, T2, const T2 *, const T2 *, const T3 *, const T4 *, T5 *, T2 *, T6 *)+0x2b0
========= by thread (32,0,0) in block (0,0,0)
========= Access to 0x7f1fa52e2f48 is misaligned
========= and is inside the nearest allocation at 0x7f1fa4000000 of size 20,971,520 bytes
========= Saved host backtrace up to driver entry point at kernel launch time
========= Host Frame: [0xa0e735] in libcusparse.so.12
========= Host Frame: [0xa74c77] in libcusparse.so.12
========= Host Frame: [0x1b4d59] in libcusparse.so.12
========= Host Frame: [0x1c5044] in libcusparse.so.12
========= Host Frame: cusparseSpMM [0xfb023] in libcusparse.so.12
========= Host Frame: at::native::bmm_out_sparse_cuda(at::Tensor const&, at::Tensor const&, at::Tensor&)::{lambda()#1}::operator()() const::{lambda()#1}::operator()() const [0x2f49e33] in libtorch_cuda.so
========= Host Frame: at::native::bmm_out_sparse_cuda(at::Tensor const&, at::Tensor const&, at::Tensor&) [0x2f4b373] in libtorch_cuda.so
========= Host Frame: at::native::bmm_sparse_cuda(at::Tensor const&, at::Tensor const&) [0x2f4d36f] in libtorch_cuda.so
========= Host Frame: at::(anonymous namespace)::(anonymous namespace)::wrapper_SparseCUDA__bmm(at::Tensor const&, at::Tensor const&) [0x3536c1b] in libtorch_cuda.so
========= Host Frame: c10::impl::wrap_kernel_functor_unboxed_<c10::impl::detail::WrapFunctionIntoFunctor_<c10::CompileTimeFunctionPointer<at::Tensor (at::Tensor const&, at::Tensor const&), &at::(anonymous namespace)::(anonymous namespace)::wrapper_SparseCUDA__bmm>, at::Tensor, c10::guts::typelist::typelist<at::Tensor const&, at::Tensor const&> >, at::Tensor (at::Tensor const&, at::Tensor const&)>::call(c10::OperatorKernel*, c10::DispatchKeySet, at::Tensor const&, at::Tensor const&) [0x3536c9e] in libtorch_cuda.so
========= Host Frame: at::_ops::bmm::redispatch(c10::DispatchKeySet, at::Tensor const&, at::Tensor const&) [0x27e8e88] in libtorch_cpu.so
========= Host Frame: torch::autograd::VariableType::(anonymous namespace)::bmm(c10::DispatchKeySet, at::Tensor const&, at::Tensor const&) [0x4d5de6a] in libtorch_cpu.so
========= Host Frame: c10::impl::wrap_kernel_functor_unboxed_<c10::impl::detail::WrapFunctionIntoFunctor_<c10::CompileTimeFunctionPointer<at::Tensor (c10::DispatchKeySet, at::Tensor const&, at::Tensor const&), &torch::autograd::VariableType::(anonymous namespace)::bmm>, at::Tensor, c10::guts::typelist::typelist<c10::DispatchKeySet, at::Tensor const&, at::Tensor const&> >, at::Tensor (c10::DispatchKeySet, at::Tensor const&, at::Tensor const&)>::call(c10::OperatorKernel*, c10::DispatchKeySet, at::Tensor const&, at::Tensor const&) [0x4d5e421] in libtorch_cpu.so
========= Host Frame: at::_ops::bmm::call(at::Tensor const&, at::Tensor const&) [0x2829c6b] in libtorch_cpu.so
========= Host Frame: torch::autograd::THPVariable_bmm(_object*, _object*, _object*) [0x59918e] in libtorch_python.so
========= Host Frame: cfunction_call in methodobject.c:537 [0x143943] in python
========= Host Frame: _PyObject_MakeTpCall in call.c:240 [0x11778b] in python
========= Host Frame: _PyEval_EvalFrameDefault in bytecodes.c:2715 [0x121951] in python
========= Host Frame: PyEval_EvalCode in ceval.c:580 [0x1de5cd] in python
========= Host Frame: run_eval_code_obj in pythonrun.c:1757 [0x21b7b6] in python
========= Host Frame: run_mod in pythonrun.c:1778 [0x216306] in python
========= Host Frame: pyrun_file in pythonrun.c:1674 [0x2131c1] in python
========= Host Frame: _PyRun_SimpleFileObject in pythonrun.c:459 [0x212d7f] in python
========= Host Frame: _PyRun_AnyFileObject in pythonrun.c:78 [0x212882] in python
========= Host Frame: Py_RunMain in main.c:714 [0x20f6c6] in python
========= Host Frame: Py_BytesMain in main.c:768 [0x1c6bb8] in python
========= Host Frame: [0x27249] in libc.so.6
========= Host Frame: __libc_start_main [0x27304] in libc.so.6
========= Host Frame: [0x1c69e8] in python
========= Host Frame: proc_batch_matrix_sparse in myfile.py:148
========= Host Frame: <module> in myfile.py:191

```

---

<div class="post-metadata">

**Author:** ![ptrblck](https://discuss.pytorch.org/user_avatar/discuss.pytorch.org/ptrblck/32/1823_2.png) [@ptrblck](https://discuss.pytorch.org/u/ptrblck)\
**Post date:** [October 23, 2025, 1:05pm UTC](https://discuss.pytorch.org/t/sparse-bmm-cause-cuda-misaligned-address-error/223661/2 "2025-10-23T13:05:11Z")

</div>

Thank you for reporting this issue! Do you see the same error using the latest stable or nightly binary with CUDA 13.0?

---

<div class="post-metadata">

**Author:** ![gimal](https://discuss.pytorch.org/user_avatar/discuss.pytorch.org/gimal/32/78480_2.png) [@gimal](https://discuss.pytorch.org/u/gimal)\
**Post date:** [October 23, 2025, 8:17pm UTC](https://discuss.pytorch.org/t/sparse-bmm-cause-cuda-misaligned-address-error/223661/3 "2025-10-23T20:17:11Z")

</div>

The error seems to occur with both latest stable and nightly with CUDA 13.0.  
Also, I’ve just found this github issue which is related [https://github.com/pytorch/pytorch/issues/119076](https://github%20issue)

And if this can be useful, I’ve made another shorter example with similar workflow to reproduce the error below. For what I have tested, pad X with zeros in dim 2 as suggested in the referenced github issue helps to bypass the error.

```auto
import torch
from torch import Tensor

torch.manual_seed(42)

def proc_batch_matrix_sparse(G: Tensor, X: Tensor) -> Tensor:
    Gt = G.transpose(1, 2)
    GtX = torch.bmm(Gt, X)
    return GtX.to("cpu")

if __name__ == " __main__":
    DTYPE = torch.float64
    GPU = True
    device = "cuda" if GPU and torch.cuda.is_available() else "cpu"

    torch.set_default_dtype(DTYPE)
    torch.set_default_device(device)

    G_shape = (3, 2779, 4)
    X_shape = (3, 2779, 1)
    density = 0.25

    X = torch.distributions.Normal(100, 50).sample(X_shape)
    G = torch.rand(G_shape)
    mask = G < density
    G[mask] = 1
    G[~mask] = 0
    G_density = G.sum() / (G_shape[0] * G_shape[1] * G_shape[2])

    G: Tensor = G.to_sparse_coo()

    print(f"{G.shape=}, {G.dtype=}, {G.device=}, {G.is_sparse=}, {G.is_coalesced()=}")
    proc_batch_matrix_sparse(G, X)

```