Therefore, let me try to help @Gavaudan (as having right, all the way, because good idea counts always). Focusing just on two (or more) Linux installations (Windows is irrelevant here) with one swap partition (with 4GB as a good number). I’ll not test this in the future either but (from what I can recall) please do not forget to adjust/have the very same (by using manual partition procedure: fdisk is good option) UUID (for both Linux distros).
mkswap --swapversion 1 -L Swap /dev/sdX8,
or if someone prefers direct approach:
mkswap --swapversion 1 -L Swap -U 8XXX888X-8888-8X8X-X888-XXXX888888XX /dev/sdX8
This above just means that someone that prepares disk(s) and its partitions: Swap partition (in particular) should not be reformatted through installer (automated) process. Not sure 100% (without testing) but IMO this might work well with two or more Linux distributions on one PC. Again, this is not step by step how-to guide, just something that needs to be considered as necessary (same UUID + reboot or shutdown usage), in order to boot again into selected distro with the same/one Swap partition.