I also encountered the same problem, so I will report it including the reproduction procedure
* Reproduction method 1. install keepalived # apt-get -y install keepalived 2. configre keepalived(interface name changed appropriately) # cat <<EOF > /etc/keepalived/keepalived.conf global_defs { notification_email { root@localhost } notification_email_from root@localhost smtp_server localhost smtp_connect_timeout 30 } vrrp_instance vi100 { state BACKUP interface enp0s8 virtual_router_id 100 garp_master_delay 1 nopreempt priority 200 advert_int 1 smtp_alert virtual_ipaddress { 10.10.10.10 } } EOF 3. start keepalived # systemctl start keepalived 4. Reload several times until a problem occurs # systemctl reload keepalived 5. problem occurs Confirmed that either event occurs * Stop keepalived process * Keepalived child process stop/start indefinitely(First reported) 6. logs /var/log/messages Jun 25 15:04:35 debian10 Keepalived_vrrp[19802]: Reloading Jun 25 15:04:35 debian10 Keepalived_vrrp[19802]: Opening file '/etc/keepalived/keepalived.conf'. Jun 25 15:04:35 debian10 Keepalived_vrrp[19806]: Registering Kernel netlink reflector Jun 25 15:04:35 debian10 Keepalived_vrrp[19806]: Registering Kernel netlink command channel Jun 25 15:04:35 debian10 Keepalived_vrrp[19806]: Opening file '/etc/keepalived/keepalived.conf'. Jun 25 15:04:35 debian10 Keepalived_vrrp[19806]: Registering gratuitous ARP shared channel Jun 25 15:04:35 debian10 Keepalived_vrrp[19806]: (vi100) Entering BACKUP STATE (init) Jun 25 15:04:35 debian10 Keepalived_vrrp[19806]: SMTP connection ERROR to [127.0.0.1]:25. Jun 25 15:04:36 debian10 Keepalived_vrrp[19806]: Reloading Jun 25 15:04:36 debian10 Keepalived_vrrp[19810]: Registering Kernel netlink reflector Jun 25 15:04:36 debian10 Keepalived_vrrp[19810]: Registering Kernel netlink command channel Jun 25 15:04:36 debian10 Keepalived_vrrp[19810]: Opening file '/etc/keepalived/keepalived.conf'. Jun 25 15:04:36 debian10 Keepalived_vrrp[19811]: Registering Kernel netlink reflector Jun 25 15:04:36 debian10 Keepalived_vrrp[19811]: Registering Kernel netlink command channel Jun 25 15:04:36 debian10 Keepalived_vrrp[19811]: Opening file '/etc/keepalived/keepalived.conf'. Jun 25 15:04:36 debian10 Keepalived_vrrp[19812]: Registering Kernel netlink reflector Jun 25 15:04:36 debian10 Keepalived_vrrp[19812]: Registering Kernel netlink command channel Jun 25 15:04:36 debian10 Keepalived_vrrp[19812]: Opening file '/etc/keepalived/keepalived.conf'. Jun 25 15:04:36 debian10 Keepalived_vrrp[19813]: Registering Kernel netlink reflector Jun 25 15:04:36 debian10 Keepalived_vrrp[19813]: Registering Kernel netlink command channel /var/log/daemon.log Jun 25 15:04:35 debian10 systemd[1]: Reloading Keepalive Daemon (LVS and VRRP). Jun 25 15:04:35 debian10 Keepalived[19732]: Reloading ... Jun 25 15:04:35 debian10 Keepalived[19732]: Opening file '/etc/keepalived/keepalived.conf'. Jun 25 15:04:35 debian10 keepalived[19732]: malloc(): smallbin double linked list corrupted Jun 25 15:04:35 debian10 Keepalived[19732]: Keepalived_vrrp exited due to signal 6 Jun 25 15:04:35 debian10 Keepalived[19732]: VRRP child process(19802) died: Respawning Jun 25 15:04:35 debian10 Keepalived[19732]: Starting VRRP child process, pid=19806 Jun 25 15:04:35 debian10 systemd[1]: Reloaded Keepalive Daemon (LVS and VRRP). Jun 25 15:04:36 debian10 systemd[1]: Reloading Keepalive Daemon (LVS and VRRP). Jun 25 15:04:36 debian10 Keepalived[19732]: Reloading ... Jun 25 15:04:36 debian10 Keepalived[19732]: Opening file '/etc/keepalived/keepalived.conf'. Jun 25 15:04:36 debian10 keepalived[19732]: malloc(): smallbin double linked list corrupted Jun 25 15:04:36 debian10 Keepalived[19732]: Keepalived_vrrp exited due to signal 6 Jun 25 15:04:36 debian10 Keepalived[19732]: VRRP child process(19806) died: Respawning Jun 25 15:04:36 debian10 Keepalived[19732]: Starting VRRP child process, pid=19810 Jun 25 15:04:36 debian10 systemd[1]: Reloaded Keepalive Daemon (LVS and VRRP). Jun 25 15:04:36 debian10 keepalived[19732]: malloc(): smallbin double linked list corrupted Jun 25 15:04:36 debian10 Keepalived[19732]: Keepalived_vrrp exited due to signal 6 Jun 25 15:04:36 debian10 Keepalived[19732]: VRRP child process(19810) died: Respawning Jun 25 15:04:36 debian10 Keepalived[19732]: Starting VRRP child process, pid=19811 Jun 25 15:04:36 debian10 keepalived[19732]: malloc(): smallbin double linked list corrupted Jun 25 15:04:36 debian10 Keepalived[19732]: Keepalived_vrrp exited due to signal 6 Jun 25 15:04:36 debian10 Keepalived[19732]: VRRP child process(19811) died: Respawning Jun 25 15:04:36 debian10 Keepalived[19732]: Starting VRRP child process, pid=19812 Jun 25 15:04:36 debian10 keepalived[19732]: malloc(): smallbin double linked list corrupted Jun 25 15:04:36 debian10 Keepalived[19732]: Keepalived_vrrp exited due to signal 6 Jun 25 15:04:36 debian10 Keepalived[19732]: VRRP child process(19812) died: Respawning Jun 25 15:04:36 debian10 Keepalived[19732]: Starting VRRP child process, pid=19813 Jun 25 15:04:36 debian10 keepalived[19732]: malloc(): smallbin double linked list corrupted Jun 25 15:04:36 debian10 Keepalived[19732]: Keepalived_vrrp exited due to signal 6 Jun 25 15:04:36 debian10 Keepalived[19732]: VRRP child process(19813) died: Respawning Jun 25 15:04:36 debian10 Keepalived[19732]: Starting VRRP child process, pid=19814 Jun 25 15:04:36 debian10 keepalived[19732]: malloc(): smallbin double linked list corrupted Jun 25 15:04:36 debian10 Keepalived[19732]: Keepalived_vrrp exited due to signal 6 -- System Information: Debian Release: 10.4 APT prefers stable-updates APT policy: (500, 'stable-updates'), (500, 'stable') Architecture: amd64 (x86_64) Kernel: Linux 4.19.0-5-amd64 (SMP w/1 CPU core) Kernel taint flags: TAINT_CRAP Locale: LANG=ja_JP.UTF-8, LC_CTYPE=ja_JP.UTF-8 (charmap=UTF-8), LANGUAGE=ja_JP.UTF-8 (charmap=UTF-8) Shell: /bin/sh linked to /usr/bin/dash Init: systemd (via /run/systemd/system) LSM: AppArmor: enabled Versions of packages keepalived depends on: ii iproute2 4.20.0-2 ii libc6 2.28-10 ii libglib2.0-0 2.58.3-2+deb10u2 ii libip4tc0 1.8.2-4 ii libip6tc0 1.8.2-4 ii libjson-c3 0.12.1+ds-2 ii libnl-3-200 3.4.0-1 ii libnl-genl-3-200 3.4.0-1 ii libsnmp30 5.7.3+dfsg-5 ii libssl1.1 1.1.1d-0+deb10u3 ii libxtables12 1.8.2-4 Versions of packages keepalived recommends: ii ipvsadm 1:1.29-1 keepalived suggests no packages.