What is a soft lockup?

[Zac Tolley]

I'm running a fc5 box, with a bunch of disks and opennms, which puts  
a high workload on the disks. Not running raid.

In /var/logl/messages i get and error like this repeatedl. The box is  
a dual xeon and it seems like each cpu in turn shows this error.

what does it mean?



Jul  2 04:00:21 opennms kernel: BUG: soft lockup detected on CPU#2!
Jul  2 04:00:21 opennms kernel: CPU 2:
Jul  2 04:00:21 opennms kernel: Modules linked in: loop ipv6 ppdev  
autofs4 hidp rfcomm l2cap bluetooth sunrpc ip_conntrack_netbios_ns  
ipt_REJECT xt_state ip_conntrack nfnetlink xt_tcpudp iptable_filter  
ip_tables x_tables video button battery ac lp parport_pc parport  
floppy nvram uhci_hcd ehci_hcd e1000 tg3 hw_random e752x_edac edac_mc  
dm_snapshot dm_zero dm_mirror dm_mod ext3 jbd cciss mptspi mptscsih  
sd_mod scsi_mod mptbase
Jul  2 04:00:21 opennms kernel: Pid: 27, comm: kblockd/2 Not tainted  
2.6.15-1.2054_FC5 #1
Jul  2 04:00:21 opennms kernel: RIP: 0010:[<ffffffff8033b86a>]  
<ffffffff8033b86a>{_spin_unlock_irqrestore+11}
Jul  2 04:00:21 opennms kernel: RSP: 0018:ffff81015b435e08  EFLAGS:  
00000247
Jul  2 04:00:21 opennms kernel: RAX: 0000000000000002 RBX:  
0000000000000247 RCX: ffff81015a4d2850
Jul  2 04:00:21 opennms kernel: RDX: 0000000000000002 RSI:  
0000000000000247 RDI: ffff81015a40b3d8
Jul  2 04:00:21 opennms kernel: RBP: ffff81015a4d2938 R08:  
ffff81015a4d28a0 R09: ffff81015a4d2800
Jul  2 04:00:21 opennms kernel: R10: 00000000dffe0000 R11:  
ffff81015a40b000 R12: ffff81015b4118c0
Jul  2 04:00:21 opennms kernel: R13: 0000000000000247 R14:  
ffff81015b028ce8 R15: ffffffff801fd5c7
Jul  2 04:00:21 opennms kernel: FS:  0000000000000000(0000)  
GS:ffff81015bf256c0(0000) knlGS:0000000000000000
Jul  2 04:00:21 opennms kernel: CS:  0010 DS: 0018 ES: 0018 CR0:  
000000008005003b
Jul  2 04:00:21 opennms kernel: CR2: 00002b78d369f000 CR3:  
0000000000101000 CR4: 00000000000006e0
Jul  2 04:00:21 opennms kernel:
Jul  2 04:00:21 opennms kernel: Call Trace: <ffffffff801425e1> 
{run_workqueue+159} <ffffffff80142c7a>{worker_thread+0}
Jul  2 04:00:21 opennms kernel:        <ffffffff80145ca3> 
{keventd_create_kthread+0} <ffffffff80142d83>{worker_thread+265}
Jul  2 04:00:21 opennms kernel:        <ffffffff8012959c> 
{__wake_up_common+62} <ffffffff8012ad74>{default_wake_function+0}
Jul  2 04:00:21 opennms kernel:        <ffffffff80145ca3> 
{keventd_create_kthread+0} <ffffffff80145fb6>{kthread+254}
Jul  2 04:00:21 opennms kernel:        <ffffffff8010b8e6>{child_rip 
+8} <ffffffff80145ca3>{keventd_create_kthread+0}
Jul  2 04:00:21 opennms kernel:        <ffffffff80339fce> 
{thread_return+0} <ffffffff80145eb8>{kthread+0}
Jul  2 04:00:21 opennms kernel:        <ffffffff8010b8de>{child_rip+0}