starting any container with umask 007 breaks host system shutdown. lxc-stop just hangs.
Affects | Status | Importance | Assigned to | Milestone | |
---|---|---|---|---|---|
linux (Ubuntu) |
Confirmed
|
Undecided
|
Unassigned |
Bug Description
If I have umask 007 (or any other value that masks the world-execute bit) when I run lxc-start for the first time after logging in, my host system enters a state with the following problems:
* lxc-stop hangs forever instead of stopping any container, even one that wasn't started with umask 007.
* lxc-stop --kill --nolock hangs in the same way.
* Attempts to reboot or shut down the host system fail, requiring a hard reset to recover.
When lxc-stop hangs, messages like these appear in syslog every couple of minutes:
Nov 17 01:22:11 hostbox kernel: [ 3360.091624] INFO: task systemd:12179 blocked for more than 120 seconds.
Nov 17 01:22:11 hostbox kernel: [ 3360.091629] Tainted: P OE 4.4.0-47-generic #68-Ubuntu
Nov 17 01:22:11 hostbox kernel: [ 3360.091631] "echo 0 > /proc/sys/
Nov 17 01:22:11 hostbox kernel: [ 3360.091633] systemd D ffff8800c6febb58 0 12179 12168 0x00000104
Nov 17 01:22:11 hostbox kernel: [ 3360.091638] ffff8800c6febb58 ffff8800d318d280 ffff88040c649b80 ffff8800d318d280
Nov 17 01:22:11 hostbox kernel: [ 3360.091641] ffff8800c6fec000 ffff8800345bc088 ffff8800345bc070 ffffffff00000000
Nov 17 01:22:11 hostbox kernel: [ 3360.091644] fffffffe00000001 ffff8800c6febb70 ffffffff81830f15 ffff8800d318d280
Nov 17 01:22:11 hostbox kernel: [ 3360.091647] Call Trace:
Nov 17 01:22:11 hostbox kernel: [ 3360.091653] [<ffffffff81830
Nov 17 01:22:11 hostbox kernel: [ 3360.091657] [<ffffffff81833
Nov 17 01:22:11 hostbox kernel: [ 3360.091662] [<ffffffff81289
Nov 17 01:22:11 hostbox kernel: [ 3360.091666] [<ffffffff81403
Nov 17 01:22:11 hostbox kernel: [ 3360.091669] [<ffffffff81833
Nov 17 01:22:11 hostbox kernel: [ 3360.091672] [<ffffffff81210
Nov 17 01:22:11 hostbox kernel: [ 3360.091674] [<ffffffff81210
Nov 17 01:22:11 hostbox kernel: [ 3360.091677] [<ffffffff81289
Nov 17 01:22:11 hostbox kernel: [ 3360.091680] [<ffffffff81289
Nov 17 01:22:11 hostbox kernel: [ 3360.091685] [<ffffffff81118
Nov 17 01:22:11 hostbox kernel: [ 3360.091687] [<ffffffff81211
Nov 17 01:22:11 hostbox kernel: [ 3360.091691] [<ffffffff8122d
Nov 17 01:22:11 hostbox kernel: [ 3360.091694] [<ffffffff81230
Nov 17 01:22:11 hostbox kernel: [ 3360.091698] [<ffffffff81231
Nov 17 01:22:11 hostbox kernel: [ 3360.091701] [<ffffffff81834
When system shutdown hangs, similar messages appear on the console every couple of minutes.
I can reproduce this at will with a freshly-installed and fully-updated host OS in VirtualBox, and with either an old-ish container or a new one.
I'm running lxc 2.0.5-0ubuntu1~
My containers are all unprivileged.
My umask at container creation time does not seem to matter. As far as I have seen, my umask only matters the first time I start a container in my login session.
I can work around the bug by manually setting my umask to something more permissive before I start my first container of the day, and then setting it back again, but that's rather a hassle. (Even worse, it's very easy to forget this workaround and be left with containers that can't be stopped and a host system that won't shut down cleanly.)
Possibly related: when the problem is triggered, I notice that my guest instances start with no /etc/resolv.conf and no inet address.