[root@alarm ~]# uname -a
Linux alarm 4.8.0-rc1-1-ARCH #1 SMP Tue Aug 9 20:58:29 MDT 2016 armv7l GNU/Linux

[root@alarm ~]# [  481.787397] INFO: task kworker/3:1:93 blocked for more than 120 seconds.
[  481.794124]       Tainted: G        WC      4.8.0-rc1-1-ARCH #1
[  481.800071] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[  481.807912] kworker/3:1     D c0aecdf4     0    93      2 0x00000000
[  481.814315] Workqueue: events_freezable mmc_rescan
[  481.819146] [<c0aecdf4>] (__schedule) from [<c0aed254>] (schedule+0x44/0x9c)
[  481.826211] [<c0aed254>] (schedule) from [<c08f14dc>] (__mmc_claim_host+0xbc/0x1dc)
[  481.833883] [<c08f14dc>] (__mmc_claim_host) from [<c08f93c8>] (mmc_sd_detect+0x1c/0x70)
[  481.841898] [<c08f93c8>] (mmc_sd_detect) from [<c08f3fec>] (mmc_rescan+0x1b0/0x378)
[  481.849569] [<c08f3fec>] (mmc_rescan) from [<c015b7b0>] (process_one_work+0x1ec/0x418)
[  481.857498] [<c015b7b0>] (process_one_work) from [<c015c4d8>] (worker_thread+0x38/0x594)
[  481.865599] [<c015c4d8>] (worker_thread) from [<c01615d0>] (kthread+0xec/0x104)
[  481.872924] [<c01615d0>] (kthread) from [<c0107d18>] (ret_from_fork+0x14/0x3c)