nginx设置和codeigniter显示空白页面

Question

我在nginx中有这样的设置：

location ~ \.php$ {
         try_files $uri =404;
         fastcgi_pass unix:/tmp/php5-fpm.sock;
         fastcgi_index index.php;
         fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
         #fastcgi_param SCRIPT_FILENAME $request_filename;
         include fastcgi_params;
    }


    location / {
            # First attempt to serve request as file, then
            # as directory, then fall back to displaying a 404.
            try_files $uri $uri/ /index.html;
            # Uncomment to enable naxsi on this location
            # include /etc/nginx/naxsi.rules

            #kill cache
            add_header Last-Modified $date_gmt;
            add_header Cache-Control 'no-store, no-cache, must-revalidate, proxy-revalidate, max-age=0';
            if_modified_since off;
            expires off;
            etag off;
    }

但它只显示空白页，nginx日志和codeigniter日志中没有错误.. 有谁知道这个？