kern/59761: dmsetup broken in 10.1 with default GENERIC kernel

[medwards-netbsd%mirkwood.net@localhost]

>Number:         59761
>Category:       kern
>Synopsis:       dmsetup broken in 10.1 with default GENERIC kernel
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Sun Nov 16 01:00:00 +0000 2025
>Originator:     Mike Edwards
>Release:        10.1
>Organization:
N/A
>Environment:
NetBSD netbsd02 10.1 NetBSD 10.1 (GENERIC) #0: Mon Dec 16 13:08:11 UTC 2024  mkrepro%mkrepro.NetBSD.org@localhost:/usr/src/sys/arch/amd64/compile/GENERIC amd64

>Description:
dmsetup fails to work, causing lvm to similarly break while attempting to create an LV, though PV and VG creation appear to work.

This is easily seen with dmsetup --version or dmsetup ls:
[ksh] root@netbsd02# dmsetup --version    
Library version:   1.02.40 (2009-11-24)
ioctl version call failed with errno 25

Command failed
[ksh] root@netbsd02# dmsetup ls           
ioctl version call failed with errno 25

Command failed


ktruss reports the ioctl that fails is NETBSD_DM_IOCTL:
  1650   1650 dmsetup  ioctl(0x4, NETBSD_DM_IOCTL, 0x7f7fffd5e1b0) Err#25 ENOTTY

Module 'dm' is loaded:
[ksh] root@netbsd02# modstat dm
NAME                       CLASS    SOURCE   FLAG  REFS    SIZE REQUIRES 
dm                         driver   filesys  -        0   18216 dk_subr

Without checking the source, I can see references to NETBSD_DM_IOCTL in the dm module, as expected:
[ksh] root@netbsd02# grep -r NETBSD_DM_IOCTL /stand/                                                                                                         
Binary file /stand/amd64/10.1/modules/dm/dm.kmod matches

I can't find a reason this ioctl should fail, given that the dm module is indeed loaded, which tells me that this driver appears to have broken at some point.
>How-To-Repeat:
Run dmstat --version or dmstat ls, watch for ioctl call to fail.
>Fix:
Unknown.