North Korea Round Trip From London, through Malaysia and disembark in China

Hi all,
Just a bit confused...
I will be flying LHR-KUL-PEK...PEK-FNJ-PEK...-PEK-KUL-LHR
Will this be ok for me to get the 72 hour visa exemption? As I am flying London to China (transiting Malaysia) getting off at Beijing for 1 night and exact same routing on return back from Pyongyang. The airlines are VERY cautious in London to check onward visas.
Thanks,
Ryan