I am setting up a standard LEMP stack. My current setup is giving me the following error:

502 Bad Gateway

This is what is currently installed on my server:

Here's the configurations I've created/updated so far, can some one take a look at the following and see where the error might be? I've already checked my logs, there's nothing in there (http://i.imgur.com/iRq3ksb.png). And I saw the following in /var/log/php-fpm/error.log file.

sidenote: both the nginx and php-fpm has been configured to run under a local account called www-data and the following folders exits on the server

nginx.conf global nginx configuration

user                    www-data;
worker_processes        6;
worker_rlimit_nofile    100000;
error_log               /var/log/nginx/error.log crit;
pid                     /var/run/nginx.pid;

events {
    worker_connections 2048;
    use epoll;
    multi_accept on;
}

http {
    include       /etc/nginx/mime.types;
    default_type  application/octet-stream;

    # cache informations about FDs, frequently accessed files can boost performance
    open_file_cache max=200000 inactive=20s; 
    open_file_cache_valid 30s; 
    open_file_cache_min_uses 2;
    open_file_cache_errors on;

    # to boost IO on HDD we can disable access logs
    access_log off;

    # copies data between one FD and other from within the kernel
    # faster then read() + write()
    sendfile on;

    # send headers in one peace, its better then sending them one by one 
    tcp_nopush on;

    # don't buffer data sent, good for small data bursts in real time
    tcp_nodelay on;

    # server will close connection after this time
    keepalive_timeout 60;

    # number of requests client can make over keep-alive -- for testing
    keepalive_requests 100000;

    # allow the server to close connection on non responding client, this will free up memory
    reset_timedout_connection on;

    # request timed out -- default 60
    client_body_timeout 60;

    # if client stop responding, free up memory -- default 60
    send_timeout 60;

    # reduce the data that needs to be sent over network
    gzip on;
    gzip_min_length 10240;
    gzip_proxied expired no-cache no-store private auth;
    gzip_types text/plain text/css text/xml text/javascript application/x-javascript application/xml;
    gzip_disable "MSIE [1-6]\.";

    # Load vHosts
    include /etc/nginx/conf.d/*.conf;
}

conf.d/www.domain.com.conf my vhost entry

## Nginx php-fpm Upstream
upstream wwwdomaincom {
    server unix:/var/run/php-fcgi-www-data.sock;
}

## Global Config
client_max_body_size            10M;
server_names_hash_bucket_size   64;

## Web Server Config
server
{
    ## Server Info
    listen 80;
    server_name domain.com *.domain.com;
    root /home/www-data/public_html;
    index index.html index.php;

    ## Error log
    error_log /home/www-data/logs/nginx-errors.log;

    ## DocumentRoot setup
    location / {
        try_files $uri $uri/ @handler;
        expires 30d;
    }

    ## These locations would be hidden by .htaccess normally
    #location /app/                       { deny all; }

    ## Disable .htaccess and other hidden files
    location  /. {
        return 404;
    }

    ## Magento uses a common front handler
    location @handler {
        rewrite / /index.php;
    }

    ## Forward paths like /js/index.php/x.js to relevant handler
    location ~ .php/ {
        rewrite ^(.*.php)/ $1 last;
    }

    ## Execute PHP scripts
    location ~ \.php$ {
        try_files $uri =404;
        expires        off;
        fastcgi_read_timeout 900;
        fastcgi_pass   wwwdomaincom;
        fastcgi_param  SCRIPT_FILENAME  $document_root$fastcgi_script_name;
        include        fastcgi_params;
    }

    ## GZip Compression
    gzip on;
    gzip_comp_level 8;
    gzip_min_length 1000;
    gzip_proxied any;
    gzip_types text/plain application/xml text/css text/js application/x-javascript;
}

/etc/php-fpm.d/www-data.conf my php-fpm pool config

## Nginx php-fpm Upstream
upstream wwwdomaincom {
    server unix:/var/run/php-fcgi-www-data.sock;
}

## Global Config
client_max_body_size            10M;
server_names_hash_bucket_size   64;

## Web Server Config
server
{
    ## Server Info
    listen 80;
    server_name domain.com *.domain.com;
    root /home/www-data/public_html;
    index index.html index.php;

    ## Error log
    error_log /home/www-data/logs/nginx-errors.log;

    ## DocumentRoot setup
    location / {
        try_files $uri $uri/ @handler;
        expires 30d;
    }

    ## These locations would be hidden by .htaccess normally
    #location /app/                       { deny all; }

    ## Disable .htaccess and other hidden files
    location  /. {
        return 404;
    }

    ## Magento uses a common front handler
    location @handler {
        rewrite / /index.php;
    }

    ## Forward paths like /js/index.php/x.js to relevant handler
    location ~ .php/ {
        rewrite ^(.*.php)/ $1 last;
    }

    ## Execute PHP scripts
    location ~ \.php$ {
        try_files $uri =404;
        expires        off;
        fastcgi_read_timeout 900;
        fastcgi_pass   wwwdomaincom;
        fastcgi_param  SCRIPT_FILENAME  $document_root$fastcgi_script_name;
        include        fastcgi_params;
    }

    ## GZip Compression
    gzip on;
    gzip_comp_level 8;
    gzip_min_length 1000;
    gzip_proxied any;
    gzip_types text/plain application/xml text/css text/js application/x-javascript;
}

I've got a file in /home/www-data/public_html/index.php with the code <?php phpinfo(); ?> (file uploaded as user www-data).