This test is described as:
# Test very basic thin device usage, exhaustion, and growth
And seems to hang like this:
generic/347 74s ... [ 701.658856] run fstests generic/347 at 2018-12-10 21:05:23
[ 701.845672] XFS (nvme0n1): Mounting V5 Filesystem
[ 702.048278] XFS (nvme0n1): Ending clean mount
[ 702.184992] XFS (nvme1n1): Unmounting Filesystem
[ 702.453064] device-mapper: thin: Data device (dm-1) discard unsupported: Disabling discard passdown.
[ 847.533607] INFO: task dmsetup:28965 blocked for more than 120 seconds.
[ 847.536715] Not tainted 4.20.0-rc6+ #4
[ 847.538857] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 847.542613] dmsetup D 0 28965 28695 0x00000000
[ 847.545405] Call Trace:
[ 847.548500] ? __schedule+0x2e6/0xb00
[ 847.550331] schedule+0x27/0x70
[ 847.551977] io_schedule+0x11/0x40
[ 847.553991] dm_wait_for_completion+0xbe/0xd0
[ 847.556151] ? wait_woken+0x80/0x80
[ 847.558165] __dm_suspend+0x90/0x1e0
[ 847.559888] dm_internal_suspend_noflush+0x90/0xe0
[ 847.562380] pool_presuspend+0x41/0x60
[ 847.564626] suspend_targets+0x45/0xa0
[ 847.566783] __dm_suspend+0xe0/0x1e0
[ 847.568454] ? table_clear+0xb0/0xb0
[ 847.570289] dm_suspend+0xd3/0x110
[ 847.572218] ? up_read+0x17/0x90
[ 847.573960] dev_suspend+0x148/0x250
[ 847.575671] ctl_ioctl+0x1a7/0x3a0
[ 847.577413] ? _raw_spin_lock_irqsave_nested+0x10/0x40
[ 847.579895] dm_ctl_ioctl+0x5/0x10
[ 847.581580] do_vfs_ioctl+0xa0/0x6a0
[ 847.583299] ksys_ioctl+0x5b/0x90
[ 847.584739] __x64_sys_ioctl+0x11/0x20
[ 847.586701] do_syscall_64+0x4b/0x180
[ 847.588679] entry_SYSCALL_64_after_hwframe+0x49/0xbe
[ 847.590450] RIP: 0033:0x7f3b400a2f07
[ 847.591709] Code: Bad RIP value.
[ 847.592688] RSP: 002b:00007ffc29d632f8 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
[ 847.595091] RAX: ffffffffffffffda RBX: 000055fbf64e0b00 RCX: 00007f3b400a2f07
[ 847.597344] RDX: 000055fbf64e0b00 RSI: 00000000c138fd06 RDI: 0000000000000003
[ 847.599027] RBP: 000000000000000c R08: 00007f3b405bc648 R09: 00007ffc29d63160
[ 847.600660] R10: 00007f3b405bbb53 R11: 0000000000000246 R12: 000055fbf64e0b30
[ 847.602441] R13: 00007f3b405bbb53 R14: 000055fbf64e0940 R15: 0000000000000000
[ 847.604404]
[ 847.604404] Showing all locks held in the system:
[ 847.605655] 1 lock held by khungtaskd/620:
[ 847.606542] #0: 00000000253d4c96 (rcu_read_lock){....}, at: debug_show_all_locks+0x15/0x175
[ 847.608204] 1 lock held by in:imklog/3712:
[ 847.608979] #0: 00000000af869ccd (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x3f/0x50
[ 847.610629] 2 locks held by dmsetup/28965:
[ 847.611410] #0: 00000000e234e2ee (&md->suspend_lock/1){+.+.}, at: dm_suspend+0x22/0x110
[ 847.613066] #1: 00000000756de3cd (&md->suspend_lock#2){+.+.}, at: dm_internal_suspend_noflush+0xc/0xe0
[ 847.614989]
[ 847.615323] =============================================
[ 847.615323]
