On Sat, Aug 14, 2021 at 02:13:09PM -0700, Guenter Roeck wrote:

On Wed, Aug 04, 2021 at 11:41:43AM +0200, Christoph Hellwig wrote:

quoted

device mapper needs to register holders before it is ready to do I/O.
Currently it does so by registering the disk early, which can leave
the disk and queue in a weird half state where the queue is registered
with the disk, except for sysfs and the elevator.  And this state has
been a bit promlematic before, and will get more so when sorting out
the responsibilities between the queue and the disk.

Support registering holders on an initialized but not registered disk
instead by delaying the sysfs registration until the disk is registered.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Mike Snitzer <redacted>

This patch results in lockdep splats when booting from flash.
Reverting it fixes the proboem.

Should be fixed by:
https://git.kernel.dk/cgit/linux-block/commit/?h=for-5.15/drivers&id=6e4df4c6488165637b95b9701cc862a42a3836ba