There was an unfortunate error while changing the kernel.org primary/secondary mirroring infrastructure, which resulted in the /pub tree suddenly becoming empty. No data was lost, just public mirror copies. Everything is now being restored, but deletes are fast and restores are slow, so thank you for your patience!

EDITED: You can follow the official incident here: https://status.linuxfoundation.org/incidents/3y1k8b4ky71t