Almost everyday my server is crashing due to hight server load, and even restarting apache or mysql can't solve the problem. I need to reboot the server to solve, or it crash again due to the high load.

The log system records something like this when it crashes:

Aug 11 18:33:53 server kernel: INFO: task httpd:20008 blocked for more than 120 seconds.
Aug 11 18:33:53 server kernel: "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
Aug 11 18:33:53 server kernel: httpd         D ffffffff801538ac     0 20008   5816         20066 19809 (NOTLB)
Aug 11 18:33:53 server kernel:  ffff81025a299dc8 0000000000000082 ffff81033b4c0740 ffffffff80009a14
Aug 11 18:33:53 server kernel:  ffff8101063f8d80 0000000000000009 ffff8100b758f7e0 ffff8101c57187e0
Aug 11 18:33:53 server kernel:  00009436d4100b6c 000000000001d50f ffff8100b758f9c8 000000083b531588
Aug 11 18:33:53 server kernel: Call Trace:
Aug 11 18:33:53 server kernel:  [<ffffffff80009a14>] __link_path_walk+0x173/0xfb9
Aug 11 18:33:53 server kernel:  [<ffffffff8002cc16>] mntput_no_expire+0x19/0x89
Aug 11 18:33:53 server kernel:  [<ffffffff80063c4f>] __mutex_lock_slowpath+0x60/0x9b
Aug 11 18:33:53 server kernel:  [<ffffffff80023908>] __path_lookup_intent_open+0x56/0x97
Aug 11 18:33:53 server kernel:  [<ffffffff80063c99>] .text.lock.mutex+0xf/0x14
Aug 11 18:33:53 server kernel:  [<ffffffff8001b21f>] open_namei+0xea/0x712
Aug 11 18:33:54 server kernel:  [<ffffffff8002768a>] do_filp_open+0x1c/0x38
Aug 11 18:33:54 server kernel: Firewall: *UDP_IN Blocked* IN=eth1 OUT= MAC=ff:ff:ff:ff:ff:ff:00:30:48:9e:6e:99:08:00 SRC=208.43.135.158 DST=255.255.255.255 LEN=151 TOS=0x00 PREC=0x00 TTL=64 ID=0 DF PROTO=UDP SPT=38354 DPT=6112 LEN=131 
Aug 11 18:33:54 server kernel:  [<ffffffff8001a061>] do_sys_open+0x44/0xbe
Aug 11 18:33:54 server kernel:  [<ffffffff8005d28d>] tracesys+0xd5/0xe0

I googled a lot trying to find a solution. But it looks that the solution is just to update the kernel or disk driver, thinks that I don't know how to do.

In this url http://bugs.centos.org/view.php?id=4515 a lot o people report similar problems, except the fact that they are not related to httpd like mine.

According to one member, one solution would be to add "elevator=noop " to /etc/grub.conf like in this example:

title CentOS (2.6.18-238.12.1.el5xen)
        root (hd0,0)
        kernel /vmlinuz-2.6.18-238.12.1.el5xen ro root=/dev/VolGroup00/LogVol00 elevator=noop
        initrd /initrd-2.6.18-238.12.1.el5xen.img

Would this really solve the problem? My disk are working in RAID. Can this cause some problem to my server?

Is there any other solution?