CentOSのBug Trackerをチェックすると、以下のバグ報告がありました。
どうやら、CentOS6.2 (x86_64) が対象で、まだ未解決のようです。

Jan  8 20:44:53 cloud-berry kernel: ————[ cut here ]————
Jan  8 20:44:53 cloud-berry kernel: WARNING: at kernel/sched.c:5914 thread_return+0×232/0x79d() (Not tainted)
Jan  8 20:44:53 cloud-berry kernel: Hardware name: Bochs
Jan  8 20:44:53 cloud-berry kernel: Modules linked in: ipt_REJECT nf_conntrack_ipv4 nf_defrag_ipv4 iptable_filter ip_tables ip6t_REJECT nf_conntrack_ipv6 nf_defrag_ipv6 xt_state nf_conntrack ip6table_filter ip6_tables ipv6 e1000 i2c_piix4 i2c_core sg ext4 mbcache jbd2 sr_mod cdrom sd_mod crc_t10dif pata_acpi ata_generic ata_piix dm_mirror dm_region_hash dm_log dm_mod [last unloaded: scsi_wait_scan]
Jan  8 20:44:53 cloud-berry kernel: Pid: 1337, comm: mysqld Not tainted 2.6.32-220.2.1.el6.x86_64 #1
Jan  8 20:44:53 cloud-berry kernel: Call Trace: Jan  8 20:44:53 cloud-berry kernel: [<ffffffff81069997>] ? warn_slowpath_common+0×87/0xc0
Jan  8 20:44:53 cloud-berry kernel: [<ffffffff810699ea>] ? warn_slowpath_null+0x1a/0×20
Jan  8 20:44:53 cloud-berry kernel: [<ffffffff814eccc5>] ? thread_return+0×232/0x79d
Jan  8 20:44:53 cloud-berry kernel: [<ffffffff811bf282>] ? read_events+0x2e2/0×450
Jan  8 20:44:53 cloud-berry kernel: [<ffffffff81056623>] ? perf_event_task_sched_out+0×33/0×80 Jan  8 20:44:53 cloud-berry kernel: [<ffffffff8105e770>] ? default_wake_function+0×0/0×20
Jan  8 20:44:53 cloud-berry kernel: [<ffffffff811bd9c0>] ? timeout_func+0×0/0×20
Jan  8 20:44:53 cloud-berry kernel: [<ffffffff811bf45b>] ? sys_io_getevents+0x6b/0xb0
Jan  8 20:44:53 cloud-berry kernel: [<ffffffff8100b0f2>] ? system_call_fastpath+0×16/0x1b
Jan  8 20:44:53 cloud-berry kernel: —[ end trace c466f39285427f59 ]—

http://cloud-berry.jp/wordpress/?p=46

CentOS Bug Tracker
0005371: ABRT WARNING: at kernel/sched.c:5914 thread_return+0×232/0x79d() (Not tainted)
http://bugs.centos.org/view.php?id=5371