[dm-devel] 'multipath add path' returns ok but the path is missing in the topology

[Martin Wilck]

On Fri, 2020-04-24 at 15:18 +0200, Gioh Kim wrote:
> 
> I would like to inform you of what I found out.
> 1. 'multipathd add path sdx' is executed
> 2. Adding thd sdx also creates a map.
> 3. The multipathd daemon waits for the change uevent from kernel.
> 4. Another sd device sdy is added with 'multipathd add path sdy'
> command
> 5. adding sdy is not done and multipathd prints a message "sdy:
> orphan
> path, waiting for create to complete"
> 6. Something (I guess it is the checker thread) removes and adds the
> dm device
> 7. sdy is removed with a message "sdy: orphan path, path removed
> externally". I guess the checker thread removes sdy as well.
> 
> I am not sure what removes the dm device and sdy device.
> I guess it would be the check thread due to the "sdy: orphan path,
> path removed externally" message.
> 
> Therefore I just added the 'udevadm settle' command after the
> 'multipathd add path sdx' command.
> So whenever my script executes 'multipathd add path', it also
> executes
> 'udevadm settle'.
> Then my test is fine for a long time.
> 
> 

This really sounds like a bug in the wait_for_udev handling.
Could you provide a full log of these events with "verbosity 3"?
No need to post it to the ML, send it privately or put it on some paste
service.

Regards
Martin