Equation, Onehalfspacing and Underfull vbox

I have a problem with an “onehalfspacing document”. Whenever I use an math environment in this document, latex notify “Underfull vbox (badness 10000) has occurred while output is active []”. I think there is a problem with another spacing between the text and the math environment different to onehalfspacing.
Exists there a global solution for the hole document to fix these vbox-problems?

I know that raggedbottom prevents, that latex stretchs the text to the pagebottom. But then I have gaps at the pagebottoms.

Here ist a MWE (where the problem occurs, but not so dramatically than in other situations):

documentclass{scrbook}
usepackage{setspace}
onehalfspacing
AfterTOCHead{singlespacing}
KOMAoptions{DIV=current}
usepackage{amsmath}
recalctypearea
%raggedbottom

%Some text:
 newcommand{sometext}{Aureh eurhg urg uhre uh uig iugh iugril giuzz geiu griugrq u gru grilu 
 geluig igru iuegg iu eh iuu gru grilu geluig igru iuehg uh uig iugh iugr geiu griugrq u gru grilu gel
 uig igru iuegg iu gruhg rg uhg ug r gr
}

begin{document}
hallo
begin{equation*}
 K(y,varepsilon)subseteq k(y,varepsilon)subseteq K(y,pvarepsilon).
end{equation*}
% Some random text:
sometextsometextsometextsometextsometextsometextsometextsometext
sometextsometextsometextsometextsometextsometextsometextsometext
end{document}