Currently, if pipe is shared between lazy and non-lazy PPBs lazy migration
fails because data that should be transfered on demand is spliced into the
images. Preventing pipe sharing between PPBs of different type resolves
this issue.
In order to still minimize pipe fragmentation, we track the last pipe that
was used for certain PPB type and re-use it for the PPB of the same type.
Signed-off-by: Mike Rapoport <rppt@linux.vnet.ibm.com>
Signed-off-by: Andrei Vagin <avagin@virtuozzo.com>