Updating the kernel using CRIU and KExec http://www.linuxplumbersconf.org/2014/ocw/proposals/1893

1. “Seamless” kernel update
with CRIU & Kexec
Pavel Emelyanov
Linux Plumbers, Düsseldorf, Germany, 2014

2. 2
How (simple case)

Stop tasks that need to survive

Dump their state as a set of image files

Change kernel with Kexec

Restore tasks from image files

3. 3
How (speeding up)

Stop tasks that need to survive

Dump their state as a set of image files

Keep memory in memory

Keep image files in memfs

Collect PFNs with data

Change kernel with Kexec

Get back memory with data

Restore tasks from image files

4. 4
Known problems

Downtime is very sensitive to

IO & dirty set (can't reboot with dirty memory)

Amount of disk reads (e.g. open()-s) on restore

Need to protect mem with images from booting kernel

Subject to all issues kexec is (e.g. not all HW is supported)