as described on the mailinglist:
A recent kernel security update[1] caused some issues with our ctdb
cluster; messages like:
  | We are still serving a public IP 'x.x.x.x' that we should not be serving. Removing it
  | common/system_common.c:89 failed to open raw socket (Invalid argument)
  | Could not find which interface the ip address is hosted on. can not release it
and 
  | common/system_linux.c:344 failed to open raw socket (Invalid argument)

The corresponding parts in ctdb's code look like this:
  | s = socket(AF_INET, SOCK_RAW, htons(IPPROTO_RAW));
converting IPPROTO_RAW to 0xff00 (from strace):
  | socket(PF_INET, SOCK_RAW, 0xff00 /* IPPROTO_??? */) = -1 EINVAL (Invalid argument)

Removing htons() from both calls seems to fix the issue for us. To have the original behavior, one could use IPPROTO_IP which is 0.

[1] https://security-tracker.debian.org/tracker/CVE-2015-8543