Look at the PKGBUILD of the package to see what it installed.
Good point.
I checked it out, and it’s full of patches.
There’s even a patch for the recent kernel issue.
Since virtualbox-bin works fine, its PKGBUILD is way too long for me to investigate 
(it’s based on the cross distro run file)
Reinstalled Manjaro, and virtualbox works perfectly fine.
Someone remind me never to install virtualbox-bin ever again.