On Fri, Dec 22 2017 at 11:00am -0500,
Bart Van Assche [off-list ref] wrote:

On Fri, 2017-12-22 at 10:53 +0100, Christian Borntraeger wrote:

quoted

any quick ideas?

Hello Christian,

Was commit afc567a4977b ("dm table: fix regression from improper dm_dev_internal.count
refcount_t conversion") included in your test kernel?

Good call.  Unlikely since since he is running 4.15-rc3 but afc567a4977b
wasn't merged until after rc3; for inclusion in 4.15-rc4.