[dm-devel] Adding target device caused an alignment inconsistency

[Bart Van Assche]

On 03/01/2016 02:25 PM, Bart Van Assche wrote:
> With kernel 4.4.0 (openSuSE Tumbleweed) I see the following message
> appear systematically in the kernel log if udev reports a new path to
> multipathd:
>
> [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
>
> This did not happen with previous kernel versions. This causes the
> initiator to report the new paths as faulty until I run the following
> command:
>
> echo reconfigure | multipathd -k
>
> Is this a know issue?

(replying to my own e-mail)

After having run multipath -f + another reconfigure I noticed that the 
optimal_io_size parameter for multipath devices is zero (io_opt) but 
that blk_stack_limits() expects that that parameter is not zero. So i 
tried to repeat the test described in commit 
e9637415a92cf25ad800b7fdeddcd30cce7b44ab:

# 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

Bart.