cuda - 3D 配列でのセグメンテーション違反

Question

CUDA (200x200x100) で 3D 配列を操作しようとしています。

z 次元 (model_num) を 4 から 5 に変更した瞬間に、セグメンテーション エラーが発生します。なぜ、どうすれば修正できますか？

const int nrcells = 200;
const int nphicells = 200;
const int model_num = 5; //So far, 4 is the maximum model_num that works. At 5 and after, there is a segmentation fault

    __global__ void kernel(float* mgridb) 
{
    const unsigned long long int  i = (blockIdx.y * gridDim.x + blockIdx.x) * blockDim.x + threadIdx.x;

    if(tx >= 0 && tx < nphicells && ty >=0 && ty < nrcells && tz >= 0  && tz < model_num){
        //Do stuff with mgridb[i]
    }
}

int main (void)
{

    unsigned long long int size_matrices = nphicells*nrcells*model_num; 
    unsigned long long int mem_size_matrices = sizeof(float) * size_matrices;

    float *h_mgridb = (float *)malloc(mem_size_matrices);
    float mgridb[nphicells][nrcells][model_num];

    for(int k = 0; k < model_num; k++){
        for(int j = 0; j < nrcells; j++){
            for(int i = 0; i < nphicells; i++){
                mgridb[i][j][k] = 0;
            }
        }
    }
    float *d_mgridb;

    cudaMalloc( (void**)&d_mgridb, mem_size_matrices );
    cudaMemcpy(d_mgridb, h_mgridb, mem_size_matrices, cudaMemcpyHostToDevice);

    int threads = nphicells;
    uint3 blocks = make_uint3(nrcells,model_num,1);
    kernel<<<blocks,threads>>>(d_mgridb);
    cudaMemcpy( h_mgridb, d_mgridb, mem_size_matrices, cudaMemcpyDeviceToHost);
    cudaFree(d_mgridb);
    return 0;
}