Large database restore and stopStone after that ... exception

I got a compressed database of around 20GB (uncompressed 170GB) and tried to create the database 
from that backup. Up to and including the "commitRestore" command everything  is working ... but then 
I try to execute a stopStone and after some time I get a signal:

GemStone signal handler: signal 15 (SIGTERM), received from process 2986 userId 1000
 si_code: -6 at 1548016279, SI_TKILL, tkill system call

The database is stopped, the new database seems to be ok (page_audit shows no error). This all happens on 
Linux Mint 19.1 - and it does not happen every time.

Marten

....
 gci login: currSession 1 linked session 
successful login
 fileformat is now utf8
sourcestringclass is now Unicode16 
topaz 1> printit
SystemRepository commitRestore
%
--- 20.01.2019 21:30:44.866 CET Logging out
Restore from transaction log(s) succeeded, commitRestore not immediately preceeded by restoreFromCurrentLogs.
 WARNING: Some transactions may not be restored. (error 4048) 
=================
 GsDevKit script: stopStone webcati69_pm4
 path: /home/mf/GsDevKit_home/bin/stopStone
=================

Error running shell command: '/home/mf/GsDevKit_home/server/bin/gs/stopGemstone'
with args:
STDOUT: '--- 20.01.2019 21:30:45.720 CET ---
stopstone[Info]: GemStone version ''3.4.0''
stopstone[Info]: initiating ''webcati69_pm4'' shutdown...
--- 20.01.2019 21:30:47.735 CET Login
[Info]: Loaded /home/mf/GsDevKit_home/server/stones/webcati69_pm4/product/lib/libfloss-3.4.0-64.so
[Info]: Gave this process preference for OOM killer: wrote to /proc/2986/oom_score_adj value 250
--- 20.01.2019 21:30:47.991 CET ---
stopstone[Info]: Waiting forever for all other processes to detach the shared page cache.
--- 20.01.2019 21:30:58.006 CET ---
stopstone[Info]: Still waiting for 1 processes to detach the shared page cache.
--- 20.01.2019 21:31:08.016 CET ---
stopstone[Info]: Still waiting for 1 processes to detach the shared page cache.
'
STDERR: =================
 GsDevKit script: stopGemstone 
 path: /home/mf/GsDevKit_home/server/bin/gs/stopGemstone
=================
GemStone signal handler: signal 15 (SIGTERM), received from process 2986 userId 1000
 si_code: -6 at 1548016279, SI_TKILL, tkill system call
Error on or near line 22 :: stopGemstone :: stopGemstone 
Error: Shell command: '/home/mf/GsDevKit_home/server/bin/gs/stopGemstone' failed.