'swapon' always fails: "Invalid argument"

[Veyrdite]

'swapon' always fails to function, returning an ambigous "Invalid argument" message (which does not seem to be related to the arguments I give it). I'm not using BTRFS

Swapon for a file (inside ext4 filesystem):
$this->bbcode_second_pass_code('', '# fallocate -l 512M swapfile
# chmod 600 swapfile
# mkswap swapfile
Setting up swapspace version 1, size = 524284 KiB
no label, UUID=(too lazy to type out)
# swapon -v swapfile
swapon swapfile
swapon: /root/swapfile: found swap signature: version 1, page-size 4, same byte order
swapon: /root/swapfile: pagesize=4096, swapsize=536870912, devsize=536870912
swapon: swapfile: swapon failed: Invalid argument ')

Swapon for a single-parition USB stick:
$this->bbcode_second_pass_code('', '# mkswap /dev/sda1
etc etc
# swapon -v /dev/sda1
swapon /dev/sda1
swapon: /dev/sda1: found swap signature: version 1, page-size 4, same byte order
swapon: /dev/sda1: pagesize=4096, swapsize=15478546432, devsize=15478548480
swapon: /dev/sda1: swapon failed: Invalid argument ')
The USB swap-partition works on another computer (Arch x86-64) so I don't think the device nor mkswap is to blame.

Normally I can live without swap (2GiB of RAM tends to be enough for me) but I'm hitting OOM conditions trying to compile and link firefox. Can anyone help me?

armv7h on Series 3 Samsung Chromebook (snow). Everything up-to-date except for systemd (which causes issues). Kernel is linux-chromebook 20140525-1 (3.4.0-ARCH)

Edit: Fixed kernel version.