Comment 6 for bug 624229

I also get entries like this in /var/log/messages after dpkg's hang on sync():
kernel: [ 4918.834150] dpkg D 0000000000000000 0 6043 6022 0x00000000
kernel: [ 4918.834156] ffff880108747d38 0000000000000082 0000000000015bc0 0000000000015bc0
kernel: [ 4918.834161] ffff88011e0d4890 ffff880108747fd8 0000000000015bc0 ffff88011e0d44d0
kernel: [ 4918.834170] 0000000000015bc0 ffff880108747fd8 0000000000015bc0 ffff88011e0d4890
kernel: [ 4918.834181] Call Trace:
kernel: [ 4918.834194] [<ffffffff815583ad>] schedule_timeout+0x22d/0x300
kernel: [ 4918.834203] [<ffffffff8105df52>] ? enqueue_entity+0x122/0x1a0
kernel: [ 4918.834211] [<ffffffff8105e015>] ? enqueue_task_fair+0x45/0x90
kernel: [ 4918.834219] [<ffffffff81557656>] wait_for_common+0xd6/0x180
kernel: [ 4918.834227] [<ffffffff8105a254>] ? try_to_wake_up+0x284/0x380
kernel: [ 4918.834231] [<ffffffff8105a350>] ? default_wake_function+0x0/0x20
kernel: [ 4918.834240] [<ffffffff815577bd>] wait_for_completion+0x1d/0x20
kernel: [ 4918.834248] [<ffffffff811666d7>] sync_inodes_sb+0x87/0xb0
kernel: [ 4918.834257] [<ffffffff8116afb2>] __sync_filesystem+0x82/0x90
kernel: [ 4918.834265] [<ffffffff8116b099>] sync_filesystems+0xd9/0x130
kernel: [ 4918.834272] [<ffffffff8116b151>] sys_sync+0x21/0x40
kernel: [ 4918.834281] [<ffffffff810121b2>] system_call_fastpath+0x16/0x1b