nginx的处理过程？403.10 禁止访问：配置无效 

@红薯 你好，想跟你请教个问题：
upstream osc_http {     server 61.145.122.155:80;     #server 219.136.249.194:80 backup; }
server {     listen 80;     server_name  *.oschina.net;  

    location ~ ^/(img|css|js|scripts|stylesheets|uploads)/ {         expires 1d;         access_log off;         proxy_buffering on;         proxy_cache static;         proxy_cache_key "$host$request_uri$is_args$args";         proxy_ignore_headers "Cache-Control" "Expires";         proxy_cache_min_uses 1;         proxy_cache_valid 200 24h;         proxy_cache_use_stale http_502 http_503 http_504;         proxy_hide_header Set-Cookie;         add_header X-Cache "$upstream_cache_status";

        proxy_pass  http://osc_http;         include proxy.conf;     }

    location / {         limit_req zone=http burst=20 nodelay;         proxy_pass http://osc_http;         include proxy.conf;     }

    error_page 502 /502.html;

}
请讲解下访问 流程？