as we discussed on IRC, always reproducible in rawhide.

corosync spins 100% cpu in certain conditions when timerfd is used.

After I built libqb without timerfd also the startup logging.debug spinning is gone.

This is a consistent reproducer, using dlm_controld.

Install libqb master/corosync master rpms and dlm rpm from fedora rawhide.

corosync.conf relevant bits:

compatibility: whitetank

quorum {
    provider: corosync_votequorum
    two_node: 1
    wait_for_all: 0
    last_man_standing: 0
    auto_tie_breaker: 0
}

nodelist {
        node {
                ring0_addr: 192.168.2.193
                nodeid: 1
        }
        node {
                ring0_addr: 192.168.2.194
                nodeid: 2
        }
}

logging {
        # Log the source file and line where messages are being
        # generated. When in doubt, leave off. Potentially useful for
        # debugging.
        fileline: off
        # Log to standard error. When in doubt, set to no. Useful when
        # running in the foreground (when invoking "corosync -f")
        to_stderr: yes
        # Log to a log file. When set to "no", the "logfile" option
        # must not be set.
        to_logfile: yes
        logfile: /var/log/cluster/corosync.log
        # Log to the system log daemon. When in doubt, set to yes.
        to_syslog: yes
        # Log debug messages (very verbose). When in doubt, leave off.
        debug: on
        # Log messages with time stamps. When in doubt, set to on
        # (unless you are only logging to syslog, where double
        # timestamps can be annoying).
        timestamp: on
        logger_subsys {
                subsys: QUORUM
                debug: on
        }
        logger_subsys {
                subsys: VOTEQ
                debug: on
        }
}

On both nodes:
modprobe dlm
cd /dev
ln -sf . misc

start corosync on both nodes. I use "corosync -f" to see logging on stderr.

on node1: start dlm_controld -f0 -D

and now the spinning:

allow dlm_controld to settle on node1.

start dlm_controld -f0 -D on node2.

corosync on node2 will start spinning 100% CPU.

killing dlm_controld on node2 will NOT solve the problem.