https://github.com/dotnet/sdk/issues/10870 test sample

test.cpp

#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <assert.h>
#include <unistd.h>
#include <sys/mman.h>
#include <pthread.h> 

#define BOOL bool
#define FALSE false
#define SIZE_T size_t
#define _ASSERTE(...) assert(__VA_ARGS__)

static pthread_mutex_t flushProcessWriteBuffersMutex;
static int* s_helperPage = 0;

size_t GetVirtualPageSize()
{
    return getpagesize();
}

BOOL InitializeFlushProcessWriteBuffers()
{
    // _ASSERTE(s_helperPage == 0);
    // _ASSERTE(s_flushUsingMemBarrier == 0);

    s_helperPage = static_cast<int*>(mmap(0, GetVirtualPageSize(), PROT_READ | PROT_WRITE, MAP_ANONYMOUS | MAP_PRIVATE, -1, 0));

    if(s_helperPage == MAP_FAILED)
    {
        printf("mmap failed\n");
        return FALSE;
    }

    // Verify that the s_helperPage is really aligned to the GetVirtualPageSize()
    _ASSERTE((((SIZE_T)s_helperPage) & (GetVirtualPageSize() - 1)) == 0);

    // Locking the page ensures that it stays in memory during the two mprotect
    // calls in the FlushProcessWriteBuffers below. If the page was unmapped between
    // those calls, they would not have the expected effect of generating IPI.
    int status = mlock(s_helperPage, GetVirtualPageSize());

    if (status != 0)
    {
        printf("mlock failed: %s (%zu)\n", strerror(errno), GetVirtualPageSize());
        return FALSE;
    }

    status = pthread_mutex_init(&flushProcessWriteBuffersMutex, NULL);
    if (status != 0)
    {
        printf("mutex failed\n");
        munlock(s_helperPage, GetVirtualPageSize());
    }

    return status == 0;
}

int main()
{
    printf("%s\n", InitializeFlushProcessWriteBuffers() ? "OK" : "FAILURE");
}