PHP - nginx 502坏网关

Question

Could someone help me i get the 502 bad gateway every few seconds

The server is running on vps on debian with quadcore and 3g ram

here is the kind of error i can in the nginx log :

2012/07/23 15:06:53 [error] 2908#0: *247 recv() failed (104: Connection reset by peer) while reading response header from upstream, client: 81.255.98.253, server: www.acmslt.fr, request: "GET /category/culte/conferences/ HTTP/1.1", upstream: "fastcgi://127.0.0.1:9000", host: "acmslt.fr", referrer: "http://www.google.fr/url?sa=t&rct=j&q=mosqu%C3%A9e%20de%20savigny%20le%20temple%2077&source=web&cd=2&ved=0CFsQjBAwAQ&url=http%3A%2F%2Facmslt.fr%2Fcategory%2Fculte%2Fconferences%2F&ei=OzANUOj0HYrG0QXusf2xCg&usg=AFQjCNHxw6lN8eBnkEOYDh5ONmutLiATHA" ~ here is the nginx.conf

user www-data;
worker_processes 4;
events {
        worker_connections 1024;
       }

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

     # Hide the Nginx version number
     server_tokens off;

     # Tweeks
     sendfile on;
     tcp_nodelay off;
     tcp_nopush on;
     keepalive_timeout 5;
     client_body_timeout 10;
     client_header_timeout 10;
     send_timeout 10;
     client_max_body_size 8M;

     set_real_ip_from 127.0.0.1;
     real_ip_header X-Forwarded-For;

     gzip on;
     gzip_disable "MSIE [1-6].(?!.*SV1)";
     gzip_vary on;
     gzip_comp_level 3;
     gzip_proxied any;
     gzip_buffers 16 8k;

     include /etc/nginx/conf.d/*.conf;
     include /etc/nginx/sites-enabled/*;
  }

the website conf in the site available

server {
        listen 8080;
        server_name www.acmslt.fr acmslt.fr;
        location / {
        root /var/www/wordpress;
        index index.php index.html index.htm;
        # Rewrite rules
        if (!-e $request_filename) {
        rewrite ^(.+)$ /index.php?q=$1 last;
       }
       # Security
       # include global/security.conf;
       # W3 Total Cache
       include global/wordpress-w3-total-cache.conf;
       # PHP-FPM
       include global/php-fpm.conf;
       }
} 

then the global/php-fpm.conf

# PHP scripts -> PHP-FPM server listening on 127.0.0.1:9000
location ~ \.php$ {
                   fastcgi_pass 127.0.0.1:9000;
                   fastcgi_index index.php;
                   include fastcgi_params;
                   fastcgi_connect_timeout 60;
                   fastcgi_send_timeout 180;
                   fastcgi_read_timeout 600;
                   fastcgi_temp_file_write_size 1M;
                   fastcgi_intercept_errors on;
                   fastcgi_param SCRIPT_FILENAME $document_root$fastcgi_script_name;
                  }

the php-fpm www.conf

[www]
user = www-data
group = www-data
listen = 127.0.0.1:9000
pm = dynamic
pm.max_children = 5
pm.start_servers = 2
pm.min_spare_servers = 1
pm.max_spare_servers = 3
chdir = /

Thanks

Edit here is what i can see in the php-fpm.log

here is what i can see in the php-fpm log

[23-Jul-2012 08:13:26] NOTICE: fpm is running, pid 631
[23-Jul-2012 08:13:26] NOTICE: ready to handle connections
[23-Jul-2012 08:40:04] WARNING: [pool www] child 646 exited on signal 11 (SIGSEGV)         after 1598.101386 seconds from start
[23-Jul-2012 08:40:04] NOTICE: [pool www] child 1354 started
[23-Jul-2012 08:40:04] WARNING: [pool www] child 1354 exited on signal 11 (SIGSEGV) after 0.191254 seconds from start
[23-Jul-2012 08:40:04] NOTICE: [pool www] child 1355 started
[23-Jul-2012 08:40:20] WARNING: [pool www] child 647 exited on signal 11 (SIGSEGV) after 1614.612810 seconds from start
[23-Jul-2012 08:40:20] NOTICE: [pool www] child 1356 started
[23-Jul-2012 08:41:05] NOTICE: Finishing ...
[23-Jul-2012 08:41:05] NOTICE: exiting, bye-bye!
[23-Jul-2012 08:41:05] NOTICE: fpm is running, pid 1937
[23-Jul-2012 08:41:05] NOTICE: ready to handle connections
[23-Jul-2012 08:51:43] NOTICE: Finishing ...
[23-Jul-2012 08:51:43] NOTICE: exiting, bye-bye! 
[23-Jul-2012 08:51:43] NOTICE: fpm is running, pid 2188
[23-Jul-2012 08:51:43] NOTICE: ready to handle connections
[23-Jul-2012 09:01:42] WARNING: [pool www] child 3934 exited on signal 11 (SIGSEGV) after 325.793784 seconds from start
[23-Jul-2012 09:01:42] NOTICE: [pool www] child 3983 started
[23-Jul-2012 09:01:44] WARNING: [pool www] child 2189 exited on signal 11 (SIGSEGV) after 601.533647 seconds from start
[23-Jul-2012 09:01:44] NOTICE: [pool www] child 3984 started
[23-Jul-2012 09:01:48] WARNING: [pool www] child 2190 exited on signal 11 (SIGSEGV) after 605.045174 seconds from start
[23-Jul-2012 09:01:48] NOTICE: [pool www] child 3986 started
[23-Jul-2012 09:01:55] WARNING: [pool www] child 3984 exited on signal 11 (SIGSEGV) after 10.610551 seconds from start