On Tue, Dec 22, 2020 at 09:06:04PM +0000, Alasdair G Kergon wrote:

I have not read the background about whatever the new problem is - I'm
jumping in cold seeing this message - but from the very beginning of
device-mapper we have strongly recommended that userspace supplies the
block device in the form MAJOR:MINOR and all our own tools do that.  We
guarantee not to deadlock in these places when this is done.

We also accept the device in the form of a path name as we know there
are times when this is safe and convenient, but then we offer no
guarantees - we place the responsibility upon userspace only to do this
when it knows it is safe to do so i.e. no race and no deadlock.

644bda6f346038bce7ad3ed48f7044c10dde6d47 changes that by accepting all
kinds of weirdo formats :(