[Samba] samba getting stuck, highwatermark replication issue?

[lists]

A bit more info:

We are currently getting those errors on DC2:
> ../source4/rpc_server/drsuapi/getncchanges.c:1961: DsGetNCChanges 2nd replication on DN DC=samba,DC=company,DC=com older highwatermark (last_dn CN=a_username,CN=Users,DC=samba,DC=company,DC=com)
> ../source4/rpc_server/drsuapi/getncchanges.c:1961: DsGetNCChanges 2nd replication on DN DC=samba,DC=company,DC=com older highwatermark (last_dn CN=Schema Admins,CN=Users,DC=samba,DC=company,DC=com)
> ../source4/rpc_server/drsuapi/getncchanges.c:1961: DsGetNCChanges 2nd replication on DN DC=samba,DC=company,DC=com older highwatermark (last_dn CN=Schema Admins,CN=Users,DC=samba,DC=company,DC=com) 

and they are also causing very high cpu usage on that DC. (85 - 90%)
On the other DCs, cpu usage is normal.

Replication still going strong, so DC2 is buzy, but functional.

The pid with high cpu usage is 3155, processlist:

> root at DC2:/var/log/samba# ps aux
> USER       PID %CPU %MEM    VSZ   RSS TTY      STAT START   TIME COMMAND
> root         1  0.0  0.0  10656   800 ?        Ss   17:22   0:00 init [2]
....
> root      1732  0.0  0.0  25304   420 ?        Ss   17:22   0:00 /usr/sbin/rpc.idmapd
> root      3153  0.0  0.5 553028 45272 ?        Ss   17:49   0:00 /usr/sbin/samba -D
> root      3154  0.0  0.3 553028 32644 ?        S    17:49   0:00 /usr/sbin/samba -D
> root      3155 85.5  0.7 561376 60052 ?        R    17:49 134:29 /usr/sbin/samba -D
> root      3156  0.0  0.6 541756 49448 ?        Ss   17:49   0:00 /usr/sbin/smbd -D --option=server role check:inhibit=yes --foreground
> root      3157  0.0  0.4 557180 35124 ?        S    17:49   0:00 /usr/sbin/samba -D
> root      3158  0.0  0.3 553028 32636 ?        S    17:49   0:00 /usr/sbin/samba -D
> root      3159  3.3  0.8 554536 70464 ?        S    17:49   5:16 /usr/sbin/samba -D
> root      3160  0.1  0.4 553028 34016 ?        S    17:49   0:10 /usr/sbin/samba -D
> root      3161  0.3  0.4 557180 36440 ?        S    17:49   0:31 /usr/sbin/samba -D
> root      3162  0.1  0.4 568024 37800 ?        S    17:49   0:09 /usr/sbin/samba -D
> root      3163  0.0  0.3 553028 32636 ?        S    17:49   0:00 /usr/sbin/samba -D
> root      3164  0.0  0.4 553028 33752 ?        S    17:49   0:00 /usr/sbin/samba -D
> root      3165  0.0  0.7 557180 60000 ?        S    17:49   0:00 /usr/sbin/samba -D
> root      3166  0.0  0.4 553028 33588 ?        S    17:49   0:00 /usr/sbin/samba -D
> root      3167  0.0  0.4 553548 35232 ?        S    17:49   0:08 /usr/sbin/samba -D
> root      3170  0.0  0.5 484364 46824 ?        Ss   17:49   0:00 /usr/sbin/winbindd -D --option=server role check:inhibit=yes --foreground
> root      3171  0.0  0.3 530724 32708 ?        S    17:49   0:00 /usr/sbin/smbd -D --option=server role check:inhibit=yes --foreground
> root      3172  0.0  0.4 530740 32828 ?        S    17:49   0:00 /usr/sbin/smbd -D --option=server role check:inhibit=yes --foreground
> root      3174  0.0  0.4 541748 34048 ?        S    17:49   0:00 /usr/sbin/smbd -D --option=server role check:inhibit=yes --foreground
> root      3175  0.0  0.4 489260 35340 ?        S    17:49   0:00 /usr/sbin/winbindd -D --option=server role check:inhibit=yes --foreground
> root      3195  0.0  0.4 484364 34448 ?        S    17:49   0:00 /usr/sbin/winbindd -D --option=server role check:inhibit=yes --foreground
> root      3262  0.0  0.4 550092 38520 ?        S    17:52   0:00 /usr/sbin/smbd -D --option=server role check:inhibit=yes --foreground
> root      3856  0.0  0.4 550092 38592 ?        S    18:38   0:00 /usr/sbin/smbd -D --option=server role check:inhibit=yes --foreground
> root      4821  0.0  0.4 550116 38716 ?        S    20:06   0:00 /usr/sbin/smbd -D --option=server role check:inhibit=yes --foreground
> 1464      4976  0.0  0.4 550116 38720 ?        S    20:20   0:00 /usr/sbin/smbd -D --option=server role check:inhibit=yes --foreground
> root      5033  0.0  0.0  25216  1336 pts/0    R+   20:26   0:00 ps aux

Suggestions?