The following test hangs with RPM kernel-default-4.4.0-3.1.x86_64 (see also
kernel.org commit e9637415a92cf25ad800b7fdeddcd30cce7b44ab for the full test
description):

# modprobe scsi_debug dev_size_mb=10 num_tgts=1 opt_blks=1536
# lsscsi | grep debug
[17352:0:0:0]disk    Linux    scsi_debug       0184  /dev/sds
# cat /sys/block/sds/queue/optimal_io_size
1536
# dmsetup create node --table "0 100 linear /dev/sds 0"
(hangs in the semop() system call)
^C


Paths appear as failed after disconnecting and reconnecting multipath
controlled storage. The following message appears in the kernel log:

[958779.753012] device-mapper: table: 254:0: adding target device sdg
caused an alignment inconsistency: physical_block_size=4096,
logical_block_size=512, alignment_offset=0, start=0