Bug#781210: systemd asserts on function cg_is_empty_recursive, crashes

[Martin Pitt]

Control: severity -1 important

Hello Faidon,

thanks for your report!

I downgrade the severity to important as per
https://www.debian.org/Bugs/Developer#severities (and with #781209 we
have the bug that triggers this one); nevertheless, this is still an
important issue of course.

Faidon Liambotis [2015-03-26  4:50 +0200]:
> #6  0x00007f8fb8f6cc8f in cg_is_empty_recursive.constprop.53 (path=0x0, ignore_self=ignore_self at entry=true, controller=<synthetic pointer>)
>     at ../src/shared/cgroup-util.c:913
>         d = 0x0
>         fn = 0x7f8fba8a4d90 "\001"
>         r = <optimized out>
> #7  0x00007f8fb8ff21c3 in manager_notify_cgroup_empty (cgroup=<optimized out>, m=0x7f8fba893b50) at ../src/core/cgroup.c:978
>         u = 0x7f8fba894d30
>         r = <optimized out>
> #8  signal_agent_released (bus=<optimized out>, message=0x7f8fba8a3b40, userdata=0x7f8fba893b50, error=<optimized out>) at ../src/core/dbus.c:90
>         m = 0x7f8fba893b50
>         cgroup = 0x7f8fba923684 "/system.slice/ipsec.service"

So "cgroup" in manager_notify_cgroup_empty() is valid, and
manager_get_unit_by_cgroup(m, cgroup) returns some unit u, but
u->cgroup_path is NULL. I suppose u->id is "ipsec.service" (if you can
easily reproduce this, confirming this in gdb would be appreciated),
so as the first iteration this smells like a bug in
the cgroup_unit hashmap maintenance.

I don't get quite the same effect as you, but I can reproduce the
wrong cgroup and that "systemctl restart strongswan" leaves the old
processes around and does not actually kill them. I don't get the
assertion or crash, though.

219 in experimental behaves much better, the processes gets put into
the "strongswan.service" cgroup, and stopping, starting, restarting
works properly. Can you confirm this?

Thanks!

Martin

-- 
Martin Pitt                        | http://www.piware.de
Ubuntu Developer (www.ubuntu.com)  | Debian Developer  (www.debian.org)
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