This bug seems not to be related to GDM at all. This is a problem either
with automount, or mount.nfs4.
I did spend some time today digging around this and found out that the
hang lasts for several minutes, but then the system springs back to life
and the user list in the greeter will get populated.
Related stuff from journald (user testuser is an LDAP user, remote home; user
localadmin is local - his home is not accessible):
okt 28 16:07:17 paulus systemd[1]: Starting GNOME Display Manager...
okt 28 16:07:17 paulus systemd[1]: Started Regular background program
processing daemon.
okt 28 16:07:17 paulus automount[1566]: Starting automounter version 5.1.2,
master map /etc/auto.master
okt 28 16:07:17 paulus automount[1566]: using kernel protocol version 5.02
okt 28 16:07:17 paulus automount[1566]: lookup_nss_read_master: reading master
file /etc/auto.master
okt 28 16:07:17 paulus automount[1566]: do_init: parse(sun): init gathered
global options: (null)
okt 28 16:07:17 paulus systemd[1]: Started GNOME Display Manager.
okt 28 16:07:17 paulus automount[1566]: lookup_read_master: lookup(file): read
entry /home
okt 28 16:07:17 paulus automount[1566]: master_do_mount: mounting /home
okt 28 16:07:17 paulus automount[1566]: automount_path_to_fifo: fifo name
/var/run/autofs.fifo-home
okt 28 16:07:17 paulus automount[1566]: lookup_nss_read_map: reading map file
/etc/auto.home
okt 28 16:07:17 paulus automount[1566]: do_init: parse(sun): init gathered
global options: (null)
okt 28 16:07:18 paulus automount[1566]: mounted indirect on /home with timeout
300, freq 75 seconds
okt 28 16:07:18 paulus automount[1566]: st_ready: st_ready(): state = 0 path
/home
okt 28 16:07:18 paulus systemd[1]: Started Automounts filesystems on demand.
okt 28 16:07:18 paulus systemd[1]: Reached target Multi-User System.
okt 28 16:07:18 paulus systemd[1]: Reached target Graphical Interface.
SNIP
okt 28 16:07:37 paulus automount[1566]: handle_packet: type = 3
okt 28 16:07:37 paulus automount[1566]: handle_packet_missing_indirect: token
2, name testuser, request pid 1805
okt 28 16:07:37 paulus automount[1566]: attempting to mount entry /home/testuser
okt 28 16:07:37 paulus automount[1566]: lookup_mount: lookup(file): looking up
testuser
okt 28 16:07:37 paulus automount[1566]: lookup_mount: lookup(file): testuser ->
-fstype=nfs4,rw,intr,sec=krb5 petrus.(REDACTED):/home/&
okt 28 16:07:37 paulus automount[1566]: parse_mount: parse(sun): expanded
entry: -fstype=nfs4,rw,intr,sec=krb5 petrus.(REDACTED):/home/testuser
okt 28 16:07:37 paulus automount[1566]: parse_mount: parse(sun): gathered
options: fstype=nfs4,rw,intr,sec=krb5
okt 28 16:07:37 paulus automount[1566]: parse_mount: parse(sun):
dequote("petrus.(REDACTED):/home/testuser") -> petrus.(REDACTED):/home/testuser
okt 28 16:07:37 paulus automount[1566]: parse_mount: parse(sun): core of entry:
options=fstype=nfs4,rw,intr,sec=krb5, loc=petrus.(REDACTED):/home/testuser
okt 28 16:07:37 paulus automount[1566]: sun_mount: parse(sun): mounting root
/home, mountpoint testuser, what petrus.(REDACTED):/home/testuser, fstype nfs4,
options rw,intr,sec=krb5
okt 28 16:07:37 paulus automount[1566]: mount_mount: mount(nfs): root=/home
name=testuser what=petrus.(REDACTED):/home/testuser, fstype=nfs4,
options=rw,intr,sec=krb5
okt 28 16:07:37 paulus automount[1566]: mount_mount: mount(nfs): nfs
options="rw,intr,sec=krb5", nobind=0, nosymlink=0, ro=0
okt 28 16:07:37 paulus automount[1566]: get_nfs_info: called with host
petrus.(REDACTED)(10.0.1.98) proto 6 version 0x40
okt 28 16:07:37 paulus automount[1566]: get_nfs_info: nfs v4 rpc ping time:
0.00
okt 28 16:07:37 paulus automount[1566]: get_nfs_info: host petrus.(REDACTED)
cost 0 weight 0
okt 28 16:07:37 paulus automount[1566]: prune_host_list: selected subset of
hosts that support NFS4 over TCP
okt 28 16:07:37 paulus automount[1566]: mount_mount: mount(nfs): calling
mkdir_path /home/testuser
okt 28 16:07:37 paulus automount[1566]: mount_mount: mount(nfs): calling mount
-t nfs4 -s -o rw,intr,sec=krb5 petrus.(REDACTED):/home/testuser /home/testuser
okt 28 16:07:37 paulus automount[1566]: mount_mount: mount(nfs): mounted
petrus.(REDACTED):/home/testuser on /home/testuser
okt 28 16:07:37 paulus automount[1566]: dev_ioctl_send_ready: token = 2
okt 28 16:07:37 paulus automount[1566]: mounted /home/testuser
okt 28 16:07:37 paulus automount[1566]: st_readmap: state 1 path /home
okt 28 16:07:37 paulus automount[1566]: re-reading map for /home
okt 28 16:07:37 paulus automount[1566]: lookup_nss_read_map: reading map file
/etc/auto.home
okt 28 16:07:37 paulus automount[1566]: do_init: parse(sun): init gathered
global options: (null)
okt 28 16:07:37 paulus automount[1566]: st_ready: st_ready(): state = 4 path
/home
okt 28 16:07:37 paulus automount[1566]: handle_packet: type = 3
okt 28 16:07:37 paulus automount[1566]: handle_packet_missing_indirect: token
3, name localadmin, request pid 1805
okt 28 16:07:37 paulus
