Comment 4 for bug 628047

I was experiencing the same problem as the OP with kernel 2.6.32-24. I installed the updated kernel out of lucid-proposed (Linux 2.6.32-25-server #44-Ubuntu SMP x86_64 GNU/Linux), and I still see the same symptom, but the call trace is now different:

Sep 24 20:32:03 pharos kernel: [ 4201.442565] INFO: task dpkg:17615 blocked for more than 120 seconds.
Sep 24 20:32:03 pharos kernel: [ 4201.442862] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
Sep 24 20:32:03 pharos kernel: [ 4201.443177] dpkg D 0000000000000000 0 17615 16766 0x00000000
Sep 24 20:32:03 pharos kernel: [ 4201.443182] ffff880425eb3d38 0000000000000086 0000000000015bc0 0000000000015bc0
Sep 24 20:32:03 pharos kernel: [ 4201.443186] ffff88042a641ab0 ffff880425eb3fd8 0000000000015bc0 ffff88042a6416f0
Sep 24 20:32:03 pharos kernel: [ 4201.443190] 0000000000015bc0 ffff880425eb3fd8 0000000000015bc0 ffff88042a641ab0
Sep 24 20:32:03 pharos kernel: [ 4201.443193] Call Trace:
Sep 24 20:32:03 pharos kernel: [ 4201.443204] [<ffffffff815583ad>] schedule_timeout+0x22d/0x300
Sep 24 20:32:03 pharos kernel: [ 4201.443209] [<ffffffff8105df52>] ? enqueue_entity+0x122/0x1a0
Sep 24 20:32:03 pharos kernel: [ 4201.443212] [<ffffffff8105e015>] ? enqueue_task_fair+0x45/0x90
Sep 24 20:32:03 pharos kernel: [ 4201.443215] [<ffffffff81557656>] wait_for_common+0xd6/0x180
Sep 24 20:32:03 pharos kernel: [ 4201.443219] [<ffffffff8105a254>] ? try_to_wake_up+0x284/0x380
Sep 24 20:32:03 pharos kernel: [ 4201.443222] [<ffffffff8105a350>] ? default_wake_function+0x0/0x20
Sep 24 20:32:03 pharos kernel: [ 4201.443225] [<ffffffff815577bd>] wait_for_completion+0x1d/0x20
Sep 24 20:32:03 pharos kernel: [ 4201.443229] [<ffffffff811666d7>] sync_inodes_sb+0x87/0xb0
Sep 24 20:32:03 pharos kernel: [ 4201.443233] [<ffffffff8116afb2>] __sync_filesystem+0x82/0x90
Sep 24 20:32:03 pharos kernel: [ 4201.443236] [<ffffffff8116b099>] sync_filesystems+0xd9/0x130
Sep 24 20:32:03 pharos kernel: [ 4201.443238] [<ffffffff8116b151>] sys_sync+0x21/0x40
Sep 24 20:32:03 pharos kernel: [ 4201.443243] [<ffffffff810121b2>] system_call_fastpath+0x16/0x1b