Comment 4 for bug 1880090

From syslog:
 kili kernel: [ 842.781641] INFO: task stress-ng-dev:120415 blocked for more than 120 seconds.
 kili kernel: [ 842.781680] Tainted: G I 3.13.0-170-generic #220-Ubuntu
 kili kernel: [ 842.781703] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
 kili kernel: [ 842.781733] stress-ng-dev D ffff88085f513b80 0 120415 120411 0x00000004
 kili kernel: [ 842.781742] ffff880035e01cf0 0000000000000082 ffff8807bf75e000 0000000000013b80
 kili kernel: [ 842.781752] ffff880035e01fd8 0000000000013b80 ffff8807bf75e000 ffff88104e0c4c28
 kili kernel: [ 842.781761] fffffff200000002 ffff88104e0c4c30 ffff8807bf75e000 7fffffffffffffff
 kili kernel: [ 842.781769] Call Trace:
 kili kernel: [ 842.781786] [<ffffffff81740739>] schedule+0x29/0x70
 kili kernel: [ 842.781792] [<ffffffff8173f9f9>] schedule_timeout+0x279/0x310
 kili kernel: [ 842.781807] [<ffffffff8132383d>] ? apparmor_capable+0x1d/0x130
 kili kernel: [ 842.781817] [<ffffffff81743b68>] ldsem_down_read+0x108/0x280
 kili kernel: [ 842.781832] [<ffffffff814650a0>] tty_ldisc_ref_wait+0x20/0x50
 kili kernel: [ 842.781839] [<ffffffff8145ee08>] tty_ioctl+0x6e8/0xbf0
 kili kernel: [ 842.781853] [<ffffffff81020257>] ? __restore_xstate_sig+0x87/0x500
 kili kernel: [ 842.781862] [<ffffffff810957e5>] ? enqueue_hrtimer+0x25/0xa0
 kili kernel: [ 842.781874] [<ffffffff811dc7f3>] do_vfs_ioctl+0x2e3/0x4d0
 kili kernel: [ 842.781884] [<ffffffff81082949>] ? restore_altstack+0x19/0x30
 kili kernel: [ 842.781891] [<ffffffff811dca61>] SyS_ioctl+0x81/0xa0
 kili kernel: [ 842.781902] [<ffffffff8174d5c9>] system_call_fastpath+0x26/0x2b