Kernel report soft lockup when call the timer function tcp_keepalive_timer. Only one cpu dead lock in bh_lock_sock(sk); And all the other CPUs are idle. The kernel version is 3.0.93. And the messages: [73136.797013] BUG: soft lockup - CPU#3 stuck for 22s! [neutron-server:5728] [73136.804090] Modules linked in: ip6table_filter ip6table_raw ip6_tables iptable_raw iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi xt_tcpudp iptable_mangle iptable_nat nf_nat nf_conntrack_ipv4 nf_defrag_ipv4 edd joydev st sr_mod ide_gd_mod(N) ide_cd_mod ide_core cdrom xfs 8021q garp stp llc sch_htb af_packet softdog signo_catch(N) ipmi_devintf ipmi_si ipmi_msghandler kbox(F) iptable_filter ip_tables x_tables openvswitch nf_conntrack crc32c libcrc32c gre mperf uio nbd bonding vhost_scsi target_core_mod configfs ext4(N) jbd2 crc16 loop vhost_net macvtap macvlan tun kvm_intel kvm ipv6 ipv6_lib ahci libahci libata i2c_i801 ixgbe(X) pcspkr hio(FN) i2c_core ses dca enclosure sg rtc_cmos acpi_power_meter button container ext3 jbd mbcache dm_mirror dm_region_hash dm_log linear sd_mod crc_t10dif ehci_hcd usbcore mpt3sas usb_common scsi_transport_sas raid_class processor thermal_sys hwmon scsi_dh_emc scsi_dh_alua scsi_dh_rdac scsi_dh_hp_sw scsi_dh scsi_mod dm_snapshot dm_mod [last unloaded: iTCO_vendor_support] [73136.899222] Supported: No, Unsupported modules are loaded [73136.904927] CPU 3 [73136.906762] Modules linked in: ip6table_filter ip6table_raw ip6_tables iptable_raw iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi xt_tcpudp iptable_mangle iptable_nat nf_nat nf_conntrack_ipv4 nf_defrag_ipv4 edd joydev st sr_mod ide_gd_mod(N) ide_cd_mod ide_core cdrom xfs 8021q garp stp llc sch_htb af_packet softdog signo_catch(N) ipmi_devintf ipmi_si ipmi_msghandler kbox(F) iptable_filter ip_tables x_tables openvswitch nf_conntrack crc32c libcrc32c gre mperf uio nbd bonding vhost_scsi target_core_mod configfs ext4(N) jbd2 crc16 loop vhost_net macvtap macvlan tun kvm_intel kvm ipv6 ipv6_lib ahci libahci libata i2c_i801 ixgbe(X) pcspkr hio(FN) i2c_core ses dca enclosure sg rtc_cmos acpi_power_meter button container ext3 jbd mbcache dm_mirror dm_region_hash dm_log linear sd_mod crc_t10dif ehci_hcd usbcore mpt3sas usb_common scsi_transport_sas raid_class processor thermal_sys hwmon scsi_dh_emc scsi_dh_alua scsi_dh_rdac scsi_dh_hp_sw scsi_dh scsi_mod dm_snapshot dm_mod [last unloaded: iTCO_vendor_support] [73137.009680] Supported: No, Unsupported modules are loaded [73137.015376] [73137.017177] Pid: 5728, comm: neutron-server Tainted: GF W NX 3.0.93-0.8-default #1 To be filled by O.E.M. RH2288H V3/BC11HGSA0 [73137.029814] RIP: 0010:[<ffffffff81460158>] [<ffffffff81460158>] _raw_spin_lock+0x18/0x20 [73137.038619] RSP: 0000:ffff88307fc63e28 EFLAGS: 00000297 [73137.044212] RAX: 0000000000000001 RBX: ffff882f5d7e87d0 RCX: ffff882f5f288020 [73137.051642] RDX: 0000000000000000 RSI: ffffffff813f40d0 RDI: ffff882d351e2850 [73137.059020] RBP: ffff882d351e29b0 R08: dead000000200200 R09: ffff8828a33fa348 [73137.066441] R10: 00000000000007c7 R11: ffffffff81025b00 R12: ffffffff81468a73 [73137.073823] R13: ffff88307fc63d98 R14: ffff882d351e2800 R15: ffff882d351e2800 [73137.081255] FS: 00002b3127ea2b20(0000) GS:ffff88307fc60000(0000) knlGS:0000000000000000 [73137.089952] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [73137.095996] CR2: 00002b8ab967fb90 CR3: 00000028a3674000 CR4: 00000000001407e0 [73137.103372] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 [73137.110811] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 [73137.118241] Process neutron-server (pid: 5728, threadinfo ffff8828a368a000, task ffff8828a33fa300) [73137.127806] Stack: [73137.130133] ffffffff813f40f1 ffff882d351e29b0 ffff882d351e29b0 0000000000000100 [73137.138221] ffffffff8106f45b ffff882d351e29b0 ffff882f5f288000 0000000000000008 [73137.146199] ffff88307fc63ea0 ffffffff813f40d0 ffffffff81070873 ffff882f5f289c20 [73137.154287] Call Trace: [73137.157049] [<ffffffff813f40f1>] tcp_keepalive_timer+0x21/0x270 [73137.163364] [<ffffffff8106f45b>] call_timer_fn+0x6b/0x120 [73137.169148] [<ffffffff81070873>] run_timer_softirq+0x173/0x240 [73137.175315] [<ffffffff8106769f>] __do_softirq+0xef/0x220 [73137.181014] [<ffffffff814692dc>] call_softirq+0x1c/0x30 [73137.186631] [<ffffffff810044d5>] do_softirq+0x65/0xa0 [73137.192078] [<ffffffff81067495>] irq_exit+0xc5/0xe0 [73137.197349] [<ffffffff810268f8>] smp_apic_timer_interrupt+0x68/0xa0 [73137.203956] [<ffffffff81468a73>] apic_timer_interrupt+0x13/0x20 [73137.210261] [<00002b3126f9dee5>] 0x2b3126f9dee4