[lxc-devel] ramfs userns /proc umount2
Serge Hallyn
serge.hallyn at ubuntu.com
Wed Jul 29 13:32:22 UTC 2015
If you rebuild lxc patching that paragraph to warn but not return
failure when the umount of './proc' fails, does the container start
properly? What does /proc/self/mountinfo inside the container then
look like?
-serge
Quoting Przemyslaw Rudy (prudy1 at o2.pl):
> /proc/self/mountinfo before the lxc-start:
>
> 1 1 0:2 / / rw - rootfs rootfs rw,size=90972k,nr_inodes=22743
> 13 1 0:5 / /dev rw,relatime - devtmpfs devtmpfs rw,size=90972k,nr_inodes=22743,mode=755
> 14 1 0:4 / /proc rw,relatime - proc proc rw
> 15 13 0:11 / /dev/pts rw,relatime - devpts devpts rw,gid=5,mode=620,ptmxmode=000
> 16 13 0:13 / /dev/shm rw,relatime - tmpfs tmpfs rw,mode=777
> 17 1 0:14 / /tmp rw,relatime - tmpfs tmpfs rw
> 18 1 0:15 / /sys rw,relatime - sysfs sysfs rw
> 19 18 0:16 / /sys/fs/cgroup rw,relatime - cgroup cgroup rw,cpuset,cpuacct,memory,devices,freezer,net_cls
>
>
> On 07/29/2015 04:07 AM, Serge Hallyn wrote:
> > I suspect you're right and we should simply ignore the failure.
> >
> > Can you show /proc/self/mountinfo before the lxc-start?
> >
> > Quoting Przemyslaw Rudy (prudy1 at o2.pl):
> >> -1 is rv, errno is 22 EINVAL
> >>
> >> The log:
> >> lxc-start 40.086 INFO lxc_start_ui - lxc_start.c:main:264 - using rcfile /containers/mycnt/config
> >> lxc-start 40.087 INFO lxc_confile - confile.c:config_idmap:1376 - read uid map: type u nsid 0 hostid 100000 range 65536
> >> lxc-start 40.087 INFO lxc_confile - confile.c:config_idmap:1376 - read uid map: type g nsid 0 hostid 100000 range 65536
> >> lxc-start 40.087 WARN lxc_cgfs - cgfs.c:lxc_cgroup_get_container_info:1100 - Not attaching to cgroup cpuset unknown to /containers mycnt
> >> lxc-start 40.087 DEBUG lxc_start - start.c:setup_signal_fd:259 - sigchild handler set
> >> lxc-start 40.089 DEBUG lxc_console - console.c:lxc_console_peer_default:500 - opening /dev/tty for console peer
> >> lxc-start 40.089 DEBUG lxc_console - console.c:lxc_console_peer_default:506 - using '/dev/tty' as console
> >> lxc-start 40.089 DEBUG lxc_console - console.c:lxc_console_sigwinch_init:179 - 509 got SIGWINCH fd 9
> >> lxc-start 40.089 DEBUG lxc_console - console.c:lxc_console_winsz:88 - set winsz dstfd:6 cols:0 rows:0
> >> lxc-start 40.089 INFO lxc_start - start.c:lxc_init:451 - 'mycnt' is initialized
> >> lxc-start 40.095 DEBUG lxc_start - start.c:__lxc_start:1137 - Not dropping cap_sys_boot or watching utmp
> >> lxc-start 40.097 INFO lxc_start - start.c:resolve_clone_flags:848 - Cloning a new user namespace
> >> lxc-start 40.112 DEBUG lxc_conf - conf.c:instantiate_veth:2703 - instantiated veth 'veth-mycnt/vethNPPNHE', index is '12'
> >> lxc-start 40.112 INFO lxc_cgroup - cgroup.c:cgroup_init:65 - cgroup driver cgroupfs initing for mycnt
> >> lxc-start 40.122 DEBUG lxc_conf - conf.c:lxc_assign_network:3120 - move 'eth0' to '512'
> >> lxc-start 40.122 NOTICE lxc_start - start.c:do_start:667 - switching to gid/uid 0 in new user namespace
> >> lxc-start 40.125 DEBUG lxc_conf - conf.c:setup_rootfs:1284 - mounted '/containers/mycnt/rootfs' on '/usr/lib/lxc/rootfs'
> >> lxc-start 40.125 INFO lxc_conf - conf.c:setup_utsname:919 - 'mycnt' hostname has been setup
> >> lxc-start 40.153 DEBUG lxc_conf - conf.c:setup_netdev:2479 - 'eth0' has been setup
> >> lxc-start 40.153 INFO lxc_conf - conf.c:setup_network:2500 - network has been setup
> >> lxc-start 40.153 INFO lxc_conf - conf.c:mount_autodev:1148 - Mounting /dev under /usr/lib/lxc/rootfs
> >> lxc-start 40.153 INFO lxc_conf - conf.c:mount_autodev:1169 - Mounted tmpfs onto /usr/lib/lxc/rootfs/dev
> >> lxc-start 40.153 INFO lxc_conf - conf.c:mount_autodev:1187 - Mounted /dev under /usr/lib/lxc/rootfs
> >> lxc-start 40.153 DEBUG lxc_conf - conf.c:mount_entry:1735 - remounting /shared on /usr/lib/lxc/rootfs/tmp to respect bind or remount optios
> >> lxc-start 40.153 DEBUG lxc_conf - conf.c:mount_entry:1750 - (at remount) flags for /shared was 0, required extra flags are 0
> >> lxc-start 40.153 DEBUG lxc_conf - conf.c:mount_entry:1759 - mountflags already was 4098, skipping remount
> >> lxc-start 40.153 DEBUG lxc_conf - conf.c:mount_entry:1785 - mounted '/shared' on '/usr/lib/lxc/rootfs/tmp', type 'none'
> >> lxc-start 40.153 INFO lxc_conf - conf.c:mount_file_entries:2034 - mount points have been setup
> >> lxc-start 40.153 INFO lxc_conf - conf.c:fill_autodev:1215 - Creating initial consoles under /usr/lib/lxc/rootfs/dev
> >> lxc-start 40.153 INFO lxc_conf - conf.c:fill_autodev:1226 - Populating /dev under /usr/lib/lxc/rootfs
> >> lxc-start 40.154 INFO lxc_conf - conf.c:fill_autodev:1258 - Populated /dev under /usr/lib/lxc/rootfs
> >> lxc-start 40.154 INFO lxc_conf - conf.c:setup_dev_console:1515 - console has been setup
> >> lxc-start 40.154 INFO lxc_conf - conf.c:do_tmp_proc_mount:3576 - I am 1, /proc/self points to ''
> >> lxc-start 40.161 INFO lxc_conf - conf.c:do_tmp_proc_mount:3602 - Mounted /proc in container for security transition
> >> lxc-start 40.500 ERROR lxc_conf - conf.c:prepare_ramfs_root:1378 - Invalid argument - Unable to umount /proc
> >> lxc-start 40.500 ERROR lxc_conf - conf.c:lxc_setup:3917 - failed to set rootfs for 'mycnt'
> >> lxc-start 40.500 ERROR lxc_start - start.c:do_start:699 - failed to setup the container
> >> lxc-start 40.500 ERROR lxc_sync - sync.c:__sync_wait:51 - invalid sequence number 1. expected 2
> >> lxc-start 40.500 WARN lxc_conf - conf.c:lxc_delete_network:2996 - failed to remove interface 'eth0'
> >> lxc-start 40.515 ERROR lxc_start - start.c:__lxc_start:1164 - failed to spawn 'mycnt'
> >> lxc-start 40.669 ERROR lxc_start_ui - lxc_start.c:main:344 - The container failed to start.
> >> lxc-start 40.669 ERROR lxc_start_ui - lxc_start.c:main:348 - Additional information can be obtained by setting the --logfile and --logprio.
> >>
> >>
> >> On 07/28/2015 05:09 PM, Serge Hallyn wrote:
> >>> Quoting Przemyslaw Rudy (prudy1 at o2.pl):
> >>>> Referring to this patch:
> >>>> https://lists.linuxcontainers.org/pipermail/lxc-devel/2014-October/010604.html
> >>>>
> >>>> Starting lxc with userns in prepare_ramfs_root() I got -1 from:
> >>>
> >>> rv or errno?
> >>>
> >>>> if (umount2("./proc", MNT_DETACH)) {
> >>>>
> >>>> Shall this error be rather ignored in case of userns? Thus the same
> >>>> logic as for other mount points processed by mentioned function?
> >>>
> >>> Can you give full (-l trace -o debug.output) startup log?
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> >>>
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