I have the following function used to test the file system (yaffs2). It is called by a FreeRTOS task with a stack size of 65535. In debug mode, everything appears to work fine, but when I enable -O1, I get a hard fault immediately after printing "Testing filesystem...".

I tried changing the test size to a much lower value, thinking maybe there is a memory issue (note that the FreeRTOS heap is 7MB wide), but nothing changed. Any ideas what might be causing this?

#include <stdio.h>

#include "FreeRTOS.h"
#include "task.h"
#include "yaffs_trace.h"
#include "yaffsfs.h"

int fs_test(void)
{
    int fd;
    int test_size = 1000000;
    const char path[] = "nand/testfile.dat";
    int pattern = 0x55;
    uint8_t *test;
    uint8_t *test_read;
    uint32_t start_time, stop_time;

    DEBUG_PRINT("Testing filesystem...\n");

    fd = yaffs_open(path, O_CREAT | O_EXCL | O_WRONLY, S_IREAD | S_IWRITE);

    if(fd < 0) {
        DEBUG_PRINT("cannot create test file\n");
        return -1;
    }

    test = pvPortMalloc(test_size);
    test_read = pvPortMalloc(test_size);

    if(test == NULL || test_read == NULL) {
        DEBUG_PRINT("not enough memory\n");
        vPortFree(test);
        vPortFree(test_read);
        yaffs_close(fd);
        yaffs_rm(path);
        return -2;
    }

    memset(test, pattern, test_size);

    start_time = xTaskGetTickCount();
    yaffs_write(fd, test, test_size);
    yaffs_close(fd);
    stop_time = xTaskGetTickCount();

    DEBUG_PRINTF("Average write speed = %d kB/s\n", test_size / (stop_time-start_time));

    fd = yaffs_open(path, O_RDWR, S_IREAD | S_IWRITE);

    if(fd < 0) {
        DEBUG_PRINT("cannot open test file\n");
        vPortFree(test);
        vPortFree(test_read);
        yaffs_close(fd);
        yaffs_rm(path);
        return -1;
    }

    start_time = xTaskGetTickCount();
    yaffs_read(fd, test_read, test_size);
    yaffs_close(fd);
    stop_time = xTaskGetTickCount();

    DEBUG_PRINTF("Average read speed = %d kB/s\n", test_size / (stop_time-start_time));

    if (!memcmp(test, test_read, test_size))
        DEBUG_PRINT("file integrity test successful\n");
    else
        DEBUG_PRINT("file integrity test failed!\n");

    yaffs_rm(path);

    vPortFree(test);
    vPortFree(test_read);

    return 0;
}