journalctl -S "2016-08-07 00:00:00" | grep coredump
Aug 07 10:00:59 LianLi systemd-coredump[2950]: Process 1353 (kactivitymanage) of user 1004 dumped core.
Aug 07 10:17:28 LianLi systemd-coredump[22428]: Process 3160 (kactivitymanage) of user 1001 dumped core.
Aug 07 11:06:23 LianLi systemd-coredump[1771]: Process 22626 (kactivitymanage) of user 1000 dumped core.
Aug 07 12:42:22 LianLi systemd-coredump[6030]: Process 5143 (kactivitymanage) of user 1000 dumped core.
Aug 07 12:51:19 LianLi systemd-coredump[7457]: Process 6238 (kactivitymanage) of user 1001 dumped core.
Aug 07 18:12:11 LianLi systemd-coredump[12270]: Process 8531 (kactivitymanage) of user 1000 dumped core.
Aug 07 18:26:45 LianLi systemd-coredump[13736]: Process 12511 (kactivitymanage) of user 1001 dumped core.
Aug 07 20:33:33 LianLi systemd-coredump[15568]: Process 14264 (kactivitymanage) of user 1000 dumped core.
Aug 07 20:48:18 LianLi systemd-coredump[17791]: Process 15817 (kactivitymanage) of user 1004 dumped core.
Aug 07 20:55:22 LianLi systemd-coredump[19120]: Process 18006 (kactivitymanage) of user 1001 dumped core.
Aug 08 08:06:55 LianLi systemd-coredump[2323]: Process 1354 (kactivitymanage) of user 1001 dumped core.
Aug 08 09:08:44 LianLi systemd-coredump[4196]: Process 2718 (kactivitymanage) of user 1004 dumped core.
Aug 08 09:33:44 LianLi systemd-coredump[17891]: Process 4398 (kactivitymanage) of user 1001 dumped core.
Aug 08 10:38:25 LianLi systemd-coredump[621]: Process 18270 (kactivitymanage) of user 1004 dumped core.
Aug 08 13:15:07 LianLi systemd-coredump[4481]: Process 1015 (kactivitymanage) of user 1005 dumped core.
Aug 08 14:25:33 LianLi systemd-coredump[9380]: Process 4830 (kactivitymanage) of user 1000 dumped core.
Aug 08 14:56:16 LianLi systemd-coredump[10818]: Process 9616 (kactivitymanage) of user 1000 dumped core.


Reproducible: Always

Steps to Reproduce:
Not sure but i think
1. log in to a plasma 5 session
2. run something like "opera"
3. close opera
4. logout

Actual Results:  
Log entry - 
Aug 08 14:56:16 LianLi systemd-coredump[10818]: Process 9616 (kactivitymanage) of user 1000 dumped core.


Expected Results:  
No coredump

I'm not sure what causes the coredump but here is a snip of data from journal logs.  In the example below, all i was running was "opera" in a Plasma 5 session on tumbleweed which i closed and then logged out.  (KDE Frameworks: 5.24.0, KDE Plasma: 5.7.3,Kernel: 4.7.0-1-default, "openSUSE Tumbleweed (20160805) (x86_64)")

Aug 08 14:55:55 LianLi audit[10791]: SECCOMP auid=1000 uid=1000 gid=100 ses=8 pid=10791 comm="opera" exe="/usr/lib64/opera/opera" sig=0 arch=c000003e syscall=273 compat=0 ip=0x7fbb5d80
Aug 08 14:55:55 LianLi kernel: audit: type=1326 audit(1470664555.103:18938): auid=1000 uid=1000 gid=100 ses=8 pid=10790 comm="opera" exe="/usr/lib64/opera/opera" sig=0 arch=c000003e sy
Aug 08 14:56:10 LianLi polkitd[1360]: Unregistered Authentication Agent for unix-session:8 (system bus name :1.277, object path /org/kde/PolicyKit1/AuthenticationAgent, locale en_GB.UT
Aug 08 14:56:12 LianLi kdm[9386]: :0[9386]: pam_unix(xdm:session): session closed for user ian
Aug 08 14:56:12 LianLi audit[9386]: USER_END pid=9386 uid=0 auid=1000 ses=8 msg='op=PAM:session_close grantors=pam_loginuid,pam_limits,pam_unix,pam_umask,pam_systemd,pam_gnome_keyring,
Aug 08 14:56:12 LianLi audit[9386]: CRED_DISP pid=9386 uid=0 auid=1000 ses=8 msg='op=PAM:setcred grantors=pam_gnome_keyring,pam_unix acct="ian" exe="/usr/bin/kdm" hostname=? addr=? ter
Aug 08 14:56:12 LianLi org.kde.KScreen[9470]: The X11 connection broke (error 1). Did the X11 server die?
Aug 08 14:56:12 LianLi kernel: audit_printk_skb: 6 callbacks suppressed
Aug 08 14:56:12 LianLi kernel: audit: type=1106 audit(1470664572.622:18941): pid=9386 uid=0 auid=1000 ses=8 msg='op=PAM:session_close grantors=pam_loginuid,pam_limits,pam_unix,pam_umas
Aug 08 14:56:12 LianLi kernel: audit: type=1104 audit(1470664572.622:18942): pid=9386 uid=0 auid=1000 ses=8 msg='op=PAM:setcred grantors=pam_gnome_keyring,pam_unix acct="ian" exe="/usr
Aug 08 14:56:12 LianLi kernel: kactivitymanage[9616]: segfault at 7fc809770d10 ip 00007fc80978a3d1 sp 00007fff7e30dae8 error 4 in libQt5Sql.so.5.6.1[7fc809772000+47000]
Aug 08 14:56:12 LianLi kernel: audit: type=1701 audit(1470664572.626:18943): auid=1000 uid=1000 gid=100 ses=8 pid=9616 comm="kactivitymanage" exe="/usr/bin/kactivitymanagerd" sig=11
Aug 08 14:56:12 LianLi audit[9616]: ANOM_ABEND auid=1000 uid=1000 gid=100 ses=8 pid=9616 comm="kactivitymanage" exe="/usr/bin/kactivitymanagerd" sig=11
Aug 08 14:56:12 LianLi org.kde.kuiserver[9470]: kuiserver: Fatal IO error: client killed
Aug 08 14:56:12 LianLi org.kde.kwalletd5[9470]: The X11 connection broke (error 1). Did the X11 server die?
Aug 08 14:56:12 LianLi org.kde.kglobalaccel[9470]: The X11 connection broke (error 1). Did the X11 server die?
Aug 08 14:56:16 LianLi systemd-coredump[10818]: Process 9616 (kactivitymanage) of user 1000 dumped core.
Aug 08 14:56:16 LianLi kdm[1059]: plymouth should quit after server startup
Aug 08 14:56:17 LianLi kdm[1059]: Quitting Plymouth with transition
Aug 08 14:56:17 LianLi kdm[1059]: Is Plymouth still running? no
Aug 08 14:56:32 LianLi systemd-logind[692]: Removed session 8.