Hello,

The following script stalls at the 2nd suspend.
It's because bdput() isn't called for the suspended_bdev.

So the inode with bd_mount_sem held is just reused
in the next mapped_device device.
Then dm_suspend will try to freeze_bdev and wait forever.

Attached patch fixes this problem.

------------------------------------------------------------
#!/bin/sh -x

map=a
while true; do
  dmsetup create $map --notable
  dmsetup suspend $map
  dmsetup remove $map
done
------------------------------------------------------------

-- 
Jun'ichi Nomura, NEC Solutions (America), Inc.