[dm-crypt] Partitions on top of LUKS encrypted HD not recognized by kernel

["rainer.herrendoerfer" <rainer.herrendoerfer@belug.de>]

Hello list,

I'm experimenting with LUKS on a Gentoo-Box. I luksFormat'ted the whole
harddisk /dev/sda and luksOpen'ed as gentoo, so it appeared as
/dev/mapper/gentoo. So far so good. When I use LVM and take it as a
physical volume and set up VGs and LVs they appear in /dev/mapper
automatically.
But when trying to use normal partitions instead of LVM, parted can
mklabel and mkpart but gets a warning that the new partitions are not
known by the kernel and indeed, they don't appear in /dev/mapper.
I need to run 'kpartx -av gentoo' that they appear in /dev/mapper and
then they are normally usable. When trying to luksClose them after
unmounting them they are 'still in use' until I make the kernel to
forget them by 'kpartx -d /dev/mapper/gentoo'.
So is using partitioning on fully encrypted harddisks not supported by
LUKS at all? Or just a bug in the current version used by Gentoo which
is 1.6.5?
Thanks in advance
®ainer