Cubieboard 1 MMC card detect hang stack trace

cubieboard-mmc-cd-hang

kworker/u2:0    D c043c9e4     0     6      2 0x00000000
Workqueue: kmmcd mmc_rescan
[<c043c9e4>] (__schedule) from [<c043c410>] (schedule_timeout+0x178/0x1f4)
[<c043c410>] (schedule_timeout) from [<c043d6c0>] (wait_for_common+0xc8/0x170)
[<c043d6c0>] (wait_for_common) from [<c02c2b90>] (mmc_wait_for_req+0xb0/0x154)
[<c02c2b90>] (mmc_wait_for_req) from [<c02c2cb0>] (mmc_wait_for_cmd+0x7c/0x9c)
[<c02c2cb0>] (mmc_wait_for_cmd) from [<c02cc1f0>] (mmc_io_rw_direct_host+0x98/0x124)
[<c02cc1f0>] (mmc_io_rw_direct_host) from [<c02cc700>] (sdio_reset+0x2c/0x64)
[<c02cc700>] (sdio_reset) from [<c02c48a4>] (mmc_rescan+0x230/0x2c0)
[<c02c48a4>] (mmc_rescan) from [<c00323ec>] (process_one_work+0x110/0x368)
[<c00323ec>] (process_one_work) from [<c0032ab0>] (worker_thread+0x13c/0x3ac)
[<c0032ab0>] (worker_thread) from [<c00388d4>] (kthread+0xcc/0xe8)
[<c00388d4>] (kthread) from [<c000e4b8>] (ret_from_fork+0x14/0x3c)
INFO: task kworker/u2:0:6 blocked for more than 120 seconds.
      Not tainted 3.15.0-rc1-00056-gf7b9c0f #242