Comment 3 for bug 672759

Similar dmesg with the virtual kernel shown here. A hard power off (xm destroy) is the only way to restart the system.

[ 704.493694] scsi 0:0:0:0: Direct-Access IET VIRTUAL-DISK 0 PQ: 0 ANSI: 4
[ 704.493901] sd 0:0:0:0: Attached scsi generic sg0 type 0
[ 704.505016] sd 0:0:0:0: [sda] 3907018752 512-byte logical blocks: (2.00 TB/1.81 TiB)
[ 704.505139] sd 0:0:0:0: [sda] Write Protect is off
[ 704.505144] sd 0:0:0:0: [sda] Mode Sense: 77 00 00 08
[ 704.505384] sd 0:0:0:0: [sda] Write cache: disabled, read cache: enabled, doesn't support DPO or FUA
[ 704.505421] ------------[ cut here ]------------
[ 704.505429] WARNING: at /build/buildd/linux-2.6.35/fs/sysfs/dir.c:451 sysfs_add_one+0xc5/0x130()
[ 704.505433] sysfs: cannot create duplicate filename '/class/block/sda'
[ 704.505437] Modules linked in: crc32c iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi parport_pc ppdev binfmt_misc lp parport xen_fbfront joydev fb_sys_fops sysimgblt xen_kbdfront sysfillrect syscopyarea
[ 704.505472] Pid: 2036, comm: async/0 Not tainted 2.6.35-23-virtual #40-Ubuntu
[ 704.505476] Call Trace:
[ 704.505484] [<ffffffff810607df>] warn_slowpath_common+0x7f/0xc0
[ 704.505491] [<ffffffff81006b3d>] ? xen_force_evtchn_callback+0xd/0x10
[ 704.505497] [<ffffffff810608d6>] warn_slowpath_fmt+0x46/0x50
[ 704.505503] [<ffffffff811bf255>] sysfs_add_one+0xc5/0x130
[ 704.505509] [<ffffffff811bfaab>] sysfs_do_create_link+0x13b/0x210
[ 704.505514] [<ffffffff811bfbb3>] sysfs_create_link+0x13/0x20
[ 704.505522] [<ffffffff81384d2c>] device_add_class_symlinks+0x6c/0x100
[ 704.505527] [<ffffffff81385c58>] device_add+0x238/0x440
[ 704.505534] [<ffffffff811b6021>] register_disk+0x41/0x180
[ 704.505541] [<ffffffff812ab12c>] add_disk+0x8c/0x160
[ 704.505547] [<ffffffff813d6a9b>] sd_probe_async+0x12b/0x220
[ 704.505553] [<ffffffff810865d0>] ? async_thread+0x0/0xf0
[ 704.505558] [<ffffffff810864aa>] run_one_entry+0x7a/0x1a0
[ 704.505564] [<ffffffff8108662d>] async_thread+0x5d/0xf0
[ 704.505569] [<ffffffff81056be0>] ? default_wake_function+0x0/0x20
[ 704.505575] [<ffffffff8107eaf6>] kthread+0x96/0xa0
[ 704.505581] [<ffffffff8100aee4>] kernel_thread_helper+0x4/0x10
[ 704.505587] [<ffffffff8100a313>] ? int_ret_from_sys_call+0x7/0x1b
[ 704.505593] [<ffffffff815a4e9d>] ? retint_restore_args+0x5/0x6
[ 704.505599] [<ffffffff8100aee0>] ? kernel_thread_helper+0x0/0x10
[ 704.505603] ---[ end trace dd350111cd760489 ]---