Comment 6 for bug 931371

FYI is the call stack from the mainline kernel. It's basically the same
as for the precise kernel.

[ 241.283078] INFO: task swapper/0:1 blocked for more than 120 seconds.
[ 241.283078] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 241.283078] swapper/0 D ffffffff8180c6c0 0 1 0 0x00000000
[ 241.283078] ffff88001ed69880 0000000000000046 ffff88001ed69fd8 0000000000013600
[ 241.283078] ffff88001ed68010 0000000000013600 0000000000013600 0000000000013600
[ 241.287078] ffff88001ed69fd8 0000000000013600 ffffffff81c0d020 ffff88001ed60000
[ 241.291079] Call Trace:
[ 241.291079] [<ffffffff8111e090>] ? __lock_page+0x70/0x70
[ 241.291079] [<ffffffff8165e82f>] schedule+0x3f/0x60
[ 241.291079] [<ffffffff8165e8dc>] io_schedule+0x8c/0xd0
[ 241.291079] [<ffffffff8111e09e>] sleep_on_page+0xe/0x20
[ 241.291079] [<ffffffff8165cc0a>] __wait_on_bit_lock+0x5a/0xc0
[ 241.291079] [<ffffffff8111e087>] __lock_page+0x67/0x70
[ 241.291079] [<ffffffff81075970>] ? autoremove_wake_function+0x40/0x40
[ 241.295079] [<ffffffff811b8630>] ? blkdev_write_begin+0x30/0x30
[ 241.295079] [<ffffffff811202f4>] do_read_cache_page+0x94/0x110
[ 241.295079] [<ffffffff811203b9>] read_cache_page_async+0x19/0x20
[ 241.295079] [<ffffffff811203ce>] read_cache_page+0xe/0x20
[ 241.299079] [<ffffffff8130230d>] read_dev_sector+0x2d/0x90
[ 241.299079] [<ffffffff813033aa>] adfspart_check_ICS+0x7a/0x290
[ 241.299079] [<ffffffff813228d4>] ? snprintf+0x34/0x40
[ 241.299079] [<ffffffff81303330>] ? check_partition+0x210/0x210
[ 241.299079] [<ffffffff81303224>] check_partition+0x104/0x210
[ 241.299079] [<ffffffff81302aba>] rescan_partitions+0xda/0x310
[ 241.299079] [<ffffffff8165f54e>] ? _raw_spin_lock+0xe/0x20
[ 241.303079] [<ffffffff811b9184>] __blkdev_get+0x2d4/0x450
[ 241.303079] [<ffffffff811b935c>] blkdev_get+0x5c/0x210
[ 241.303079] [<ffffffff81301017>] register_disk+0x177/0x1a0
[ 241.303079] [<ffffffff813010e6>] add_disk+0xa6/0x1b0
[ 241.307080] [<ffffffff8164879a>] virtblk_probe+0x44c/0x4f1
[ 241.307080] [<ffffffff813b5423>] virtio_dev_probe+0xd3/0x120
[ 241.307080] [<ffffffff81407bb8>] really_probe+0x68/0x190
[ 241.307080] [<ffffffff81407d25>] driver_probe_device+0x45/0x70
[ 241.315080] [<ffffffff81407deb>] __driver_attach+0x9b/0xa0
[ 241.315080] [<ffffffff81407d50>] ? driver_probe_device+0x70/0x70
[ 241.315080] [<ffffffff81406308>] bus_for_each_dev+0x68/0x90
[ 241.319080] [<ffffffff81407a0e>] driver_attach+0x1e/0x20
[ 241.323081] [<ffffffff81407560>] bus_add_driver+0xd0/0x270
[ 241.323081] [<ffffffff81d200f5>] ? max_loop_setup+0x1a/0x1a
[ 241.323081] [<ffffffff814084a0>] driver_register+0x80/0x150
[ 241.323081] [<ffffffff81d200f5>] ? max_loop_setup+0x1a/0x1a
[ 241.327081] [<ffffffff813b5590>] register_virtio_driver+0x20/0x30
[ 241.327081] [<ffffffff81d2014c>] init+0x57/0x81
[ 241.327081] [<ffffffff81002042>] do_one_initcall+0x42/0x180
[ 241.331081] [<ffffffff81ce9681>] kernel_init+0xd2/0x156
[ 241.335081] [<ffffffff81668fe4>] kernel_thread_helper+0x4/0x10
[ 241.335081] [<ffffffff81ce95af>] ? parse_early_options+0x20/0x20
[ 241.335081] [<ffffffff81668fe0>] ? gs_change+0x13/0x13