Date: Fri, 25 Jun 2021 16:41:00 +0200 From: Michael Gmelin <freebsd@grem.de> To: jail@freebsd.org Subject: POSIX shared memory and dying jails Message-ID: <20210625164100.73c71055@bsd64.grem.de>
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Hi,
It seems like non-anonymous POSIX shared memory is not freed
automatically when a jail is removed and keeps it in a dying state,
until the shared memory segment is deleted manually.
See below for the most basic example:
[root@jailhost ~]# jail -c path=/ command=/bin/sh
# posixshmcontrol create /removeme
# exit
[root@jailhost ~]# jls -dv -j shmtest dying
true
So at this point, the jail is stuck in a dying state.
Checking POSIX shared memory segments shows the shared memory segment
which is stopping the jail from crossing the Styx:
[root@jailhost ~]# posixshmcontrol list
MODE OWNER GROUP SIZE PATH
rw------- root wheel 0 /removeme
After removing the shared memory segment manually...
[root@jailhost ~]# posixshmcontrol rm /removeme
the jail passes away peacefully:
[root@jailhost ~]# jls -dv -j shmtest dying
jls: jail "shmtest" not found
I wonder if it wouldn't make sense to always remove POSIX shared memory
created by a jail automatically when it's removed.
Best,
Michael
--
Michael Gmelin
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