早上同事反映数据库不能用。无法正常登录主机。多次尝试后终于登上主机，检查系统日志发现下述错误：

BUG: soft lockup - CPU#5 stuck for 17163091988s!
貌似是操作系统的bug.

以下是详细信息：
# uname -ra
Linux Test-DB01 2.6.32-200.13.1.el5uek #1 SMP Wed Jul 27 21:02:33 EDT 2011 x86_64 x86_64 x86_64 GNU/Linux

mysql> select version();
+------------+
| version()  |
+------------+
| 5.5.24-log |
+------------+
1 row in set (0.00 sec)

Dec 18 22:55:44 Test-Db01 kernel: Call Trace:
Dec 18 22:55:44 Test-Db01 kernel: BUG: soft lockup - CPU#5 stuck for 17163091988s! [mysqld:27243]
Dec 18 22:55:44 Test-Db01 kernel: Modules linked in: autofs4(U) i2c_dev(U) i2c_core(U) hidp(U) rfcomm(U) l2cap(U) bluetooth(U) rfkill(U) lockd(U) sunrpc(U) nf_conntrack_netbios_ns(U) ipt_REJECT(U) nf_conntrack_ipv4(U) nf_defrag_ipv4(U) xt_state(U) nf_conntrack(U) xt_tcpudp(U) ip6_tables(U) x_tables(U) be2iscsi(U) rdma_cm(U) ib_cm(U) iw_cm(U) ib_sa(U) ib_mad(U) ib_core(U) ib_addr(U) iscsi_tcp(U) bnx2i(U) cnic(U) uio(U) ipv6(U) cxgb3i(U) libcxgbi(U) cxgb3(U) libiscsi_tcp(U) libiscsi(U) scsi_transport_iscsi(U) video(U) output(U) sbs(U) sbshc(U) parport_pc(U) lp(U) parport(U) joydev(U) ses(U) enclosure(U) bnx2(U) dcdbas(U) serio_raw(U) snd_seq_dummy(U) snd_seq_oss(U) snd_seq_midi_event(U) snd_seq(U) snd_seq_device(U) snd_pcm_oss(U) snd_mixer_oss(U) snd_pcm(U) snd_timer(U) snd(U) soundcore(U) snd_page_alloc(U) iTCO_wdt(U) iTCO_vendor_support(U) pcspkr(U) usb_storage(U) shpchp(U) megaraid_sas(U) [last unloaded: ip_tables]
Dec 18 22:55:44 Test-Db01 kernel: CPU 5:
Dec 18 22:55:44 Test-Db01 kernel: Modules linked in: autofs4(U) i2c_dev(U) i2c_core(U) hidp(U) rfcomm(U) l2cap(U) bluetooth(U) rfkill(U) lockd(U) sunrpc(U) nf_conntrack_netbios_ns(U) ipt_REJECT(U) nf_conntrack_ipv4(U) nf_defrag_ipv4(U) xt_state(U) nf_conntrack(U) xt_tcpudp(U) ip6_tables(U) x_tables(U) be2iscsi(U) rdma_cm(U) ib_cm(U) iw_cm(U) ib_sa(U) ib_mad(U) ib_core(U) ib_addr(U) iscsi_tcp(U) bnx2i(U) cnic(U) uio(U) ipv6(U) cxgb3i(U) libcxgbi(U) cxgb3(U) libiscsi_tcp(U) libiscsi(U) scsi_transport_iscsi(U) video(U) output(U) sbs(U) sbshc(U) parport_pc(U) lp(U) parport(U) joydev(U) ses(U) enclosure(U) bnx2(U) dcdbas(U) serio_raw(U) snd_seq_dummy(U) snd_seq_oss(U) snd_seq_midi_event(U) snd_seq(U) snd_seq_device(U) snd_pcm_oss(U) snd_mixer_oss(U) snd_pcm(U) snd_timer(U) snd(U) soundcore(U) snd_page_alloc(U) iTCO_wdt(U) iTCO_vendor_support(U) pcspkr(U) usb_storage(U) shpchp(U) megaraid_sas(U) [last unloaded: ip_tables]
Dec 18 22:55:44 Test-Db01 kernel: Pid: 27243, comm: mysqld Not tainted 2.6.32-200.13.1.el5uek #1 PowerEdge R710
Dec 18 22:55:44 Test-Db01 kernel: RIP: 0033:[<00000000008f95a3>]  [<00000000008f95a3>] 0x8f95a3

虽然文中提到的是在Exadata X2-8 中遇到的问题. 但测试环境中的操作系统内核和错误现象bug中描述的是基本一致的。

Exadata X2-8 database servers running Unbreakable Enterprise Kernel for Oracle Linux 2.6.32-100.23.1 that have been continuously up for more than 208 days are susceptible to this problem.  Unbreakable Enterprise Kernel for Oracle Linux 2.6.32-100.23.1 is the Linux kernel provided with Exadata releases 11.2.2.2.0 through 11.2.2.4.2, inclusive.  Uptime may be determined by the uptime(1) command.

解决方案有两种;

1. 升级到新版本

Upgrade to Exadata 11.2.3.1.0 or later (Recommended).

2. 在系统运行到208天前，重启操作系统 。

Reboot database servers before uptime reaches 208 days

目前只能尝试第二种了。

出问题的是一个 ：

DELL 的PowerEdge R710 的机器，传说这个型号的机器过半年就要宕机一次。

两种bug出现在一台机器上，真是"巧合"

参考文档：
【MOS】ALERT - Exadata X2-8 systems affected by Linux bug 14258279: scheduling clock overflows in 208 days [ID 1473825.1]
【MOS】Bug 14258279 : [EXADATA] SOFT LOCKUP - CPU#0 STUCK FOR 17163091968S!