Arne Jansen wrote:

scrub_chunk failed to free all extent_maps it referenced, leading to a leak
of these maps on unmount.

Reported-by: Ilya Dryomov <idryomov@gmail.com>
Signed-off-by: Arne Jansen <redacted>

I think it's better to fold those fix-up patches into your original scrub
patchset.