CUB sum reduction with 2D pitched arrays

I am trying to perform a sum reduction using CUB and 2D arrays of type float/double. Although it works for certain combinations of rows+columns, for relatively larger arrays, I get an illegal memory access error during the last transfer. A minimal example is the following:

#include <stdio.h>
#include <stdlib.h>

#include <cub/device/device_reduce.cuh>
#include "cuda_runtime.h"

#ifdef DP
#define real double
#else
#define real float
#endif

void generatedata(const int num, real* vec, real start, real finish) {
    real rrange = finish - start;
    for (auto i = 0; i < num; ++i)
        vec[i] = rand() / float(RAND_MAX) * rrange + start;
}

real reduce_to_sum(const int num, const real* vec) {
    real total = real(0.0);
    for (auto i = 0; i < num; ++i)
        total += vec[i];

    return total;
}

int main() {
    int rows = 2001;
    int cols = 3145;
    size_t msize = rows * cols;

    real* data = (real*)malloc(msize * sizeof(real));
    if (!data)
        return -999;

    generatedata(msize, data, 0., 50.);
    real ref_sum = reduce_to_sum(msize, data);

    real* d_data_in = nullptr;
    real* d_data_out = nullptr;
    size_t pitch_in, pitch_out;
    cudaError_t err = cudaMallocPitch(&d_data_in, &pitch_in, cols * sizeof(real), rows);
    if (err != cudaSuccess) {
        printf("data_in :: %s \n", cudaGetErrorString(err));
        return -999;
    }
    err = cudaMallocPitch(&d_data_out, &pitch_out, cols * sizeof(real), rows);
    if (err != cudaSuccess) {
        printf("data_out :: %s \n", cudaGetErrorString(err));
        return -999;
    }

    err = cudaMemset(d_data_in, 0, rows * pitch_in);
    if (err != cudaSuccess) {
        printf("set data_in :: %s \n", cudaGetErrorString(err));
        return -999;
    }
    err = cudaMemcpy2D(d_data_in, pitch_in, data, cols * sizeof(real), cols * sizeof(real), rows, cudaMemcpyHostToDevice);
    if (err != cudaSuccess) {
        printf("copy data :: %s \n", cudaGetErrorString(err));
        return -999;
    }

    void* d_temp = nullptr;
    size_t   temp_bytes = 0;
    cub::DeviceReduce::Sum(d_temp, temp_bytes, d_data_in, d_data_out, rows * pitch_out);
    err = cudaMalloc(&d_temp, temp_bytes);
    if (err != cudaSuccess) {
        printf("temp :: %s \n", cudaGetErrorString(err));
        return -999;
    }

    err = cudaMemset(d_data_out, 0, rows * pitch_out);
    if (err != cudaSuccess) {
        printf("set temp :: %s \n", cudaGetErrorString(err));
        return -999;
    }
    // Run sum-reduction
    cub::DeviceReduce::Sum(d_temp, temp_bytes, d_data_in, d_data_out, rows * pitch_out);
    err = cudaGetLastError();
    if (err != cudaSuccess) {
        printf("reduction :: %s \n", cudaGetErrorString(err));
        return -999;
    }

    real gpu_sum = real(0.0);
    err = cudaMemcpy(&gpu_sum, d_data_out, sizeof(real), cudaMemcpyDeviceToHost);
    if (err != cudaSuccess) {
        printf("copy final :: %s \n", cudaGetErrorString(err));
        return -999;
    }

    printf("Difference in sum (h)%f - (d)%f = %f \n", ref_sum, gpu_sum, ref_sum - gpu_sum);

    if (data) free(data);
    if (d_data_in) cudaFree(d_data_in);
    if (d_data_out) cudaFree(d_data_out);
    if (d_temp) cudaFree(d_temp);
    cudaDeviceReset();
    return 0;
}

The error is thrown at "copy final ::". I am bit confused as to why certain rows x columns work and others don't. I did notice it's the larger values that cause it, but can't get my head around. Any suggestions would be much appreciated.

The 5th parameter of cub::DeviceReduce::Sum should be the number of input elements. However, rows * pitch_out is the size of the output buffer in bytes.

Assuming pitch_in % sizeof(real) == 0, the following call may work.

cub::DeviceReduce::Sum(d_temp, temp_bytes, d_data_in, d_data_out, rows * (pitch_in / sizeof(real)));

Also note that cub::DeviceReduce::Sum may return before the reduction is complete. In this case, if any error happened during execution, this error will be reported by cudaMemcpy.