Description of problem:
I came back to my machine after only a minute or so away, woke the screen and entered my password in the gnome-shell lock screen. My system entered a tight loop jumping between a virtual terminal and my lock screen until I eventually powered off the machine.

Version-Release number of selected component:
gdm-3.16.0.1-2.fc22

Additional info:
reporter:       libreport-2.5.1
backtrace_rating: 4
cmdline:        /usr/sbin/gdm
crash_function: get_default_session_name
executable:     /usr/sbin/gdm
global_pid:     1338
kernel:         4.0.0-0.rc5.git4.1.fc22.x86_64
runlevel:       N 5
type:           CCpp
uid:            0

Truncated backtrace:
Thread no. 1 (10 frames)
 #0 get_default_session_name at gdm-session.c:581
 #1 worker_on_saved_session_name_read at gdm-session.c:904
 #2 ffi_call_unix64 at ../src/x86/unix64.S:76
 #3 ffi_call at ../src/x86/ffi64.c:525
 #4 g_cclosure_marshal_generic at gclosure.c:1448
 #7 g_signal_emitv at gsignal.c:3044
 #8 gdm_dbus_worker_proxy_g_signal at gdm-session-worker-glue.c:3585
 #9 ffi_call_unix64 at ../src/x86/unix64.S:76
 #10 ffi_call at ../src/x86/ffi64.c:525
 #11 g_cclosure_marshal_generic at gclosure.c:1448

Potential duplicate: bug 1198610