Segmentation fault (core dumped)

Hi,

I just started programming with CUDA and I’m totally new with the environment.

as i execute the following code (adding to vectors), there is a problem: “Segmentation fault (core dumped)”

how can I fix the problem?

thanks

Hi!

remove “&” sign in cudaMemcpy calls.

I removed them, but that wasn’t solved…

Allocate h_A and h_B with

h_A = malloc(size);

 h_B = malloc(size);

Properly #including <stdlib.h> would have caught this. Along the same lines, you should provide prototypes for functions in your code. If nothing else helps, a debugger will point out which source code line causes the segmentation fault.

I have similar problem while running cuda sdk 6.5 vector add program.

  • Vector addition: C = A + B.
  • This sample is a very basic sample that implements element by element
  • vector addition. It is the same as the sample illustrating Chapter 2
  • of the programming guide with some additions like error checking.
    */

#include <stdio.h>

// For the CUDA runtime routines (prefixed with “cuda_”)
#include <cuda_runtime.h>

/**

  • CUDA Kernel Device code

  • Computes the vector addition of A and B into C. The 3 vectors have the same

  • number of elements numElements.
    */
    global void
    vectorAdd(const float *A, const float *B, float *C, int numElements)
    {
    int i = blockDim.x * blockIdx.x + threadIdx.x;

    if (i < numElements)
    {
    C[i] = A[i] + B[i];
    }
    }

/**

  • Host main routine
    */
    int
    main(void)
    {
    // Error code to check return values for CUDA calls
    cudaError_t err = cudaSuccess;

    // Print the vector length to be used, and compute its size
    int numElements = 50000;
    size_t size = numElements * sizeof(float);
    printf("[Vector addition of %d elements]\n", numElements);

    // Allocate the host input vector A
    float *h_A = (float *)malloc(size);

    // Allocate the host input vector B
    float *h_B = (float *)malloc(size);

    // Allocate the host output vector C
    float *h_C = (float *)malloc(size);

    // Verify that allocations succeeded
    if (h_A == NULL || h_B == NULL || h_C == NULL)
    {
    fprintf(stderr, “Failed to allocate host vectors!\n”);
    exit(EXIT_FAILURE);
    }

    // Initialize the host input vectors
    for (int i = 0; i < numElements; ++i)
    {
    h_A[i] = rand()/(float)RAND_MAX;
    h_B[i] = rand()/(float)RAND_MAX;
    }

    // Allocate the device input vector A
    float *d_A = NULL;
    err = cudaMalloc((void **)&d_A, size);

    if (err != cudaSuccess)
    {
    fprintf(stderr, “Failed to allocate device vector A (error code %s)!\n”, cudaGetErrorString(err));
    exit(EXIT_FAILURE);
    }

    // Allocate the device input vector B
    float *d_B = NULL;
    err = cudaMalloc((void **)&d_B, size);

    if (err != cudaSuccess)
    {
    fprintf(stderr, “Failed to allocate device vector B (error code %s)!\n”, cudaGetErrorString(err));
    exit(EXIT_FAILURE);
    }

    // Allocate the device output vector C
    float *d_C = NULL;
    err = cudaMalloc((void **)&d_C, size);

    if (err != cudaSuccess)
    {
    fprintf(stderr, “Failed to allocate device vector C (error code %s)!\n”, cudaGetErrorString(err));
    exit(EXIT_FAILURE);
    }

    // Copy the host input vectors A and B in host memory to the device input vectors in
    // device memory
    printf(“Copy input data from the host memory to the CUDA device\n”);
    err = cudaMemcpy(d_A, h_A, size, cudaMemcpyHostToDevice);

    if (err != cudaSuccess)
    {
    fprintf(stderr, “Failed to copy vector A from host to device (error code %s)!\n”, cudaGetErrorString(err));
    exit(EXIT_FAILURE);
    }

    err = cudaMemcpy(d_B, h_B, size, cudaMemcpyHostToDevice);

    if (err != cudaSuccess)
    {
    fprintf(stderr, “Failed to copy vector B from host to device (error code %s)!\n”, cudaGetErrorString(err));
    exit(EXIT_FAILURE);
    }

    // Launch the Vector Add CUDA Kernel
    int threadsPerBlock = 256;
    int blocksPerGrid =(numElements + threadsPerBlock - 1) / threadsPerBlock;
    printf(“CUDA kernel launch with %d blocks of %d threads\n”, blocksPerGrid, threadsPerBlock);
    vectorAdd<<<blocksPerGrid, threadsPerBlock>>>(d_A, d_B, d_C, numElements);
    err = cudaGetLastError();

    if (err != cudaSuccess)
    {
    fprintf(stderr, “Failed to launch vectorAdd kernel (error code %s)!\n”, cudaGetErrorString(err));
    exit(EXIT_FAILURE);
    }

    // Copy the device result vector in device memory to the host result vector
    // in host memory.
    printf(“Copy output data from the CUDA device to the host memory\n”);
    err = cudaMemcpy(h_C, d_C, size, cudaMemcpyDeviceToHost);

    if (err != cudaSuccess)
    {
    fprintf(stderr, “Failed to copy vector C from device to host (error code %s)!\n”, cudaGetErrorString(err));
    exit(EXIT_FAILURE);
    }

    // Verify that the result vector is correct
    for (int i = 0; i < numElements; ++i)
    {
    if (fabs(h_A[i] + h_B[i] - h_C[i]) > 1e-5)
    {
    fprintf(stderr, “Result verification failed at element %d!\n”, i);
    exit(EXIT_FAILURE);
    }
    }

    printf(“Test PASSED\n”);

    // Free device global memory
    err = cudaFree(d_A);

    if (err != cudaSuccess)
    {
    fprintf(stderr, “Failed to free device vector A (error code %s)!\n”, cudaGetErrorString(err));
    exit(EXIT_FAILURE);
    }

    err = cudaFree(d_B);

    if (err != cudaSuccess)
    {
    fprintf(stderr, “Failed to free device vector B (error code %s)!\n”, cudaGetErrorString(err));
    exit(EXIT_FAILURE);
    }

    err = cudaFree(d_C);

    if (err != cudaSuccess)
    {
    fprintf(stderr, “Failed to free device vector C (error code %s)!\n”, cudaGetErrorString(err));
    exit(EXIT_FAILURE);
    }

    // Free host memory
    free(h_A);
    free(h_B);
    free(h_C);

    // Reset the device and exit
    // cudaDeviceReset causes the driver to clean up all state. While
    // not mandatory in normal operation, it is good practice. It is also
    // needed to ensure correct operation when the application is being
    // profiled. Calling cudaDeviceReset causes all profile data to be
    // flushed before the application exits
    err = cudaDeviceReset();

    if (err != cudaSuccess)
    {
    fprintf(stderr, “Failed to deinitialize the device! error=%s\n”, cudaGetErrorString(err));
    exit(EXIT_FAILURE);
    }

    printf(“Done\n”);
    return 0;
    }

ERROR: Segmentation fault (core dumped)