Linux CentOS – Kernel panic

This looks like an error with memory by sim. Anyone has a better clue? The kernel version is 2.6.9-67.0.4.EL, then we rebooted and upgraded to 2.6.9-67.0.20.EL. Any kernel bug I should be aware of?

Jul 13 04:03:13 host syslogd 1.4.1: restart.
Jul 16 08:00:01 host kernel: swap_free: Unused swap offset entry 00010000
Jul 16 08:00:01 host kernel: swap_free: Unused swap offset entry 00010000
Jul 16 08:45:01 host kernel: Unable to handle kernel paging request at virtual address 313a3921
Jul 16 08:45:01 host kernel:  printing eip:
Jul 16 08:45:01 host kernel: c015eebb
Jul 16 08:45:01 host kernel: *pde = 00000000
Jul 16 08:45:01 host kernel: Oops: 0000 [#1]
Jul 16 08:45:01 host kernel: Modules linked in: ip_vs_wrr ip_vs md5 ipv6 ipt_TOS iptable_mangle ip_conntrack_ftp ip_conntrack_irc ipt_REJECT ipt_LOG ipt_limit
iptable_filter ipt_multiport ipt_state ip_conntrack ip_tables autofs4 sunrpc dm_mirror dm_mod button battery ac parport_pc parport 8139too mii ext3 jbd
Jul 16 08:45:01 host kernel: CPU:    0
Jul 16 08:45:01 host kernel: EIP:    0060:[]    Not tainted VLI
Jul 16 08:45:01 host kernel: EFLAGS: 00010202   (2.6.9-67.0.4.EL)
Jul 16 08:45:01 host kernel: EIP is at find_vma+0x29/0x4d
Jul 16 08:45:01 host kernel: eax: 313a3919   ebx: 00c8479c   ecx: 313a3931   edx: c97ec6b4
Jul 16 08:45:01 host kernel: esi: de5b40a0   edi: c8929360   ebp: bff08518   esp: c85dcef4
Jul 16 08:45:01 host kernel: ds: 007b   es: 007b   ss: 0068
Jul 16 08:45:01 host kernel: Process sim (pid: 6909, threadinfo=c85dc000 task=c8929360)
Jul 16 08:45:01 host kernel: Stack: de5b40a0 de5b40d0 c011d901 00000000 00c8479c c85dcfc4 c032ebbf 00000007
Jul 16 08:45:01 host kernel:        0000000e 0000000b 00000000 00000000 00000000 00000000 00000000 00030001
Jul 16 08:45:01 host kernel:        00000000 00000000 00000000 00000000 00000000 00000000 00000000 00000000
Jul 16 08:45:01 host kernel: Call Trace:
Jul 16 08:45:01 host kernel:  [] do_page_fault+0x114/0x4dc
Jul 16 08:45:01 host kernel:  [] do_page_fault+0x0/0x4dc
Jul 16 08:45:01 host kernel:  [] error_code+0x2f/0x38
Jul 16 08:45:01 host kernel:  [] schedule_tail+0xfd/0x106
Jul 16 08:45:01 host kernel:  [] do_page_fault+0x0/0x4dc
Jul 16 08:45:01 host kernel:  [] error_code+0x2f/0x38
Jul 16 08:45:01 host kernel: Code: 5d c3 56 89 c6 53 89 d3 31 d2 85 c0 74 3c 8b 50 08 85 d2 74 0a 39 5a 08 76 05 39 5a 04 76 2b 8b 4e 04 31 d2 85 c9 74 22 8d 4
1 e8 <39> 58 08 76 0c 39 58 04 89 c2 76 0c 8b 49 0c eb 03 8b 49 08 85
Jul 16 08:45:01 host kernel:  <0>Fatal exception: panic in 5 seconds
Jul 16 10:12:18 host syslogd 1.4.1: restart.