[CentOS] 5.10, crashes

We've just started getting this. We're running 5.10, kernel
2.6.32-358.18.1.el6.x86_64. Anyone else seen anything like this, or have
any ideas?

     mark

Nov  1 14:34:21 <server> kernel: WARNING: at block/ll_rw_blk.c:543
blk_do_ordered()
Nov  1 14:34:21 <server> kernel:
Nov  1 14:34:21 <server> kernel: Call Trace:
Nov  1 14:34:22 <server> kernel:  [<ffffffff8014defa>]
blk_do_ordered+0x27a/0x2b3
Nov  1 14:34:22 <server> kernel:  [<ffffffff8014ac82>]
elv_next_request+0x13e/0x178
Nov  1 14:34:22 <server> kernel:  [<ffffffff8807b335>]
:scsi_mod:scsi_request_fn+0x6a/0x392
Nov  1 14:34:22 <server> kernel:  [<ffffffff8005abd2>]
generic_unplug_device+0x22/0x32
Nov  1 14:34:22 <server> kernel:  [<ffffffff8004d957>]
run_workqueue+0x9e/0xfb
Nov  1 14:34:22 <server> kernel:  [<ffffffff8004a1aa>]
worker_thread+0x0/0x122
Nov  1 14:34:22 <server> kernel:  [<ffffffff800a3d4a>]
keventd_create_kthread+0x0/0xc4
Nov  1 14:34:22 <server> kernel:  [<ffffffff8004a29a>]
worker_thread+0xf0/0x122
Nov  1 14:34:22 <server> kernel:  [<ffffffff8008f4a9>]
default_wake_function+0x0/0xe
Nov  1 14:34:22 <server> kernel:  [<ffffffff800a3d4a>]
keventd_create_kthread+0x0/0xc4
Nov  1 14:34:22 <server> kernel:  [<ffffffff800a3d4a>]
keventd_create_kthread+0x0/0xc4
Nov  1 14:34:22 <server> kernel:  [<ffffffff80032c68>] kthread+0xfe/0x132
Nov  1 14:34:22 <server> kernel:  [<ffffffff8005dfc1>] child_rip+0xa/0x11
Nov  1 14:34:22 <server> kernel:  [<ffffffff800a3d4a>]
keventd_create_kthread+0x0/0xc4
Nov  1 14:34:23 <server> kernel:  [<ffffffff80032b6a>] kthread+0x0/0x132
Nov  1 14:34:23 <server> kernel:  [<ffffffff8005dfb7>] child_rip+0x0/0x11