I'm running umask 027 (set in `.bashrc` for my user, which is copied to my root session after using `su`) and can report this issue still occurs for unprivileged containers under Debian 9 (stretch, stable) using LXC 2.0.7-2+deb9u2 and kernel 4.19.0-0.bpo.4-amd64. I can also confirm umask at container creation time does not matter. Another symptom of this issue is that after it occurred, `sync` (both the utility and system call) and `update-initramfs` (which calls `sync`) start hanging.
The comments to the [launchpad bug](https://discuss.linuxcontainers.org/t/cannot-stop-unprivileged- container-not-even-kill-9-its-systemd-process-on-host/1079) by the original author of this issue and [this](https://discuss.linuxcontainers.org/t/cannot-stop-unprivileged- container-not-even-kill-9-its-systemd-process-on-host/1079) thread contain a few discussions with regards to possible reasons this occurs. Also, is #2277 perhaps related? It took a long time before I traced this down to the umask, because the symptoms are bewildering. My original issue: https://superuser.com/questions/1439108/lxc-start-stop-hangs-and-filesystem-sync-hangs/1440273 -- You received this bug notification because you are a member of Ubuntu Touch seeded packages, which is subscribed to lxc in Ubuntu. https://bugs.launchpad.net/bugs/1642767 Title: starting any container with umask 007 breaks host system shutdown. lxc-stop just hangs. Status in lxc package in Ubuntu: Confirmed 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/kernel/hung_task_timeout_secs" disables this message. 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] [<ffffffff81830f15>] schedule+0x35/0x80 Nov 17 01:22:11 hostbox kernel: [ 3360.091657] [<ffffffff81833b62>] rwsem_down_write_failed+0x202/0x350 Nov 17 01:22:11 hostbox kernel: [ 3360.091662] [<ffffffff812899a0>] ? kernfs_sop_show_options+0x40/0x40 Nov 17 01:22:11 hostbox kernel: [ 3360.091666] [<ffffffff81403fa3>] call_rwsem_down_write_failed+0x13/0x20 Nov 17 01:22:11 hostbox kernel: [ 3360.091669] [<ffffffff8183339d>] ? down_write+0x2d/0x40 Nov 17 01:22:11 hostbox kernel: [ 3360.091672] [<ffffffff812104a0>] grab_super+0x30/0xa0 Nov 17 01:22:11 hostbox kernel: [ 3360.091674] [<ffffffff81210a32>] sget_userns+0x152/0x450 Nov 17 01:22:11 hostbox kernel: [ 3360.091677] [<ffffffff81289a20>] ? kernfs_sop_show_path+0x50/0x50 Nov 17 01:22:11 hostbox kernel: [ 3360.091680] [<ffffffff81289c8e>] kernfs_mount_ns+0x7e/0x230 Nov 17 01:22:11 hostbox kernel: [ 3360.091685] [<ffffffff811187ab>] cgroup_mount+0x2eb/0x7f0 Nov 17 01:22:11 hostbox kernel: [ 3360.091687] [<ffffffff81211af8>] mount_fs+0x38/0x160 Nov 17 01:22:11 hostbox kernel: [ 3360.091691] [<ffffffff8122db57>] vfs_kern_mount+0x67/0x110 Nov 17 01:22:11 hostbox kernel: [ 3360.091694] [<ffffffff81230329>] do_mount+0x269/0xde0 Nov 17 01:22:11 hostbox kernel: [ 3360.091698] [<ffffffff812311cf>] SyS_mount+0x9f/0x100 Nov 17 01:22:11 hostbox kernel: [ 3360.091701] [<ffffffff81834ff2>] entry_SYSCALL_64_fastpath+0x16/0x71 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~ubuntu16.04.2 on xubuntu 16.04.1 LTS amd64. 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.) To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/lxc/+bug/1642767/+subscriptions -- Mailing list: https://launchpad.net/~touch-packages Post to : touch-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~touch-packages More help : https://help.launchpad.net/ListHelp
