Unexplained mount failure, protocol error, what we know so far


#21

Repeat the failed operation doesn’t work at my end… I end up installing another distro(ezgo 14, based on Kubuntu 18.04) and not encounter the issue since :-/


#22

What was the specific operation that was failing for you? Was it refresh? Installation of snaps? Something else perhaps?


#23

Installation of snaps, unfortunately I rm -rf'ed the entire system and can’t provide more info now.


#24

Which distribution release were you using when this issue was occurring?


#25

It was KDE neon Developer Edition (based on Ubuntu 18.04), not sure the exact release though(might be on the unstable branch) but it’s up-to-date.


#26

We have merged a workaround for this issue into master now (PR was https://github.com/snapcore/snapd/pull/6331) - this will be part of the 2.37 release.


#27

@zyga I’ve kinda reproduced the issue again, let’s see if we can dig it deeper.

Currently installed snap count: 34

The problem kinda emerged after I installed the core18 base snap, but who knows?


#28

I now reproduced a similar issue again, but it seems to be another cause.

The snap install and snap try command fails with protocol error when the LXD container with disk device is started:

$ lxc start snapcraft-gallery-dl

$ sudo snap install hello
error: cannot perform the following tasks:
- Mount snap "hello" (20) ([start snap-hello-20.mount] failed with exit status 1: Job for snap-hello-20.mount failed.
See "systemctl status snap-hello-20.mount" and "journalctl -xe" for details.
)

$ snap changes | tail -n2
28   Error   today at 13:11 CST      today at 13:11 CST      Install "hello" snap

$ snap tasks 28
Status  Spawn               Ready               Summary
Done    today at 13:11 CST  today at 13:11 CST  Ensure prerequisites for "hello" are available
Undone  today at 13:11 CST  today at 13:11 CST  Download snap "hello" (20) from channel "stable"
Done    today at 13:11 CST  today at 13:11 CST  Fetch and check assertions for snap "hello" (20)
Error   today at 13:11 CST  today at 13:11 CST  Mount snap "hello" (20)
Hold    today at 13:11 CST  today at 13:11 CST  Copy snap "hello" data
Hold    today at 13:11 CST  today at 13:11 CST  Setup snap "hello" (20) security profiles
Hold    today at 13:11 CST  today at 13:11 CST  Make snap "hello" (20) available to the system
Hold    today at 13:11 CST  today at 13:11 CST  Automatically connect eligible plugs and slots of snap "hello"
Hold    today at 13:11 CST  today at 13:11 CST  Set automatic aliases for snap "hello"
Hold    today at 13:11 CST  today at 13:11 CST  Setup snap "hello" aliases
Hold    today at 13:11 CST  today at 13:11 CST  Run install hook of "hello" snap if present
Hold    today at 13:11 CST  today at 13:11 CST  Start snap "hello" (20) services
Hold    today at 13:11 CST  today at 13:11 CST  Run configure hook of "hello" snap if present

......................................................................
Mount snap "hello" (20)

2019-02-22T13:11:07+08:00 ERROR [start snap-hello-20.mount] failed with exit status 1: Job for snap-hello-20.mount failed.
See "systemctl status snap-hello-20.mount" and "journalctl -xe" for details.

$ systemctl status snap-hello-20.mount
● snap-hello-20.mount
   Loaded: not-found (Reason: No such file or directory)
   Active: failed (Result: protocol) since Fri 2019-02-22 13:11:06 CST; 2min 6s ago

 2月 22 13:11:06 brlin-main systemd[1]: Mounting Mount unit for hello, revision 20...
 2月 22 13:11:06 brlin-main systemd[1]: snap-hello-20.mount: Mount process finished, but there is no mount.
 2月 22 13:11:06 brlin-main systemd[1]: snap-hello-20.mount: Failed with result 'protocol'.
 2月 22 13:11:06 brlin-main systemd[1]: Failed to mount Mount unit for hello, revision 20.

$ lxc stop snapcraft-gallery-dl

$ sudo snap install hello
hello 2.10 from Canonical✓ installed

The LXD container is somehow interfering with the mounting of the snaps:

$ mount | grep gallerynsfs on /run/snapd/ns/gallery-dl.mnt type nsfs (rw)
/dev/sdb4 on /snap/gallery-dl/x4 type ext4 (ro,relatime,errors=remount-ro,data=ordered,x-gdu.hide)
/dev/sdb4 on /snap/gallery-dl/x5 type ext4 (ro,relatime,errors=remount-ro,data=ordered,x-gdu.hide)
/dev/sdb4 on /snap/gallery-dl/x6 type ext4 (ro,relatime,errors=remount-ro,data=ordered,x-gdu.hide)
/dev/sdb4 on /var/lib/lxd/devices/snapcraft-gallery-dl/disk.Snapcraft config.home-ubuntu-.config-snapcraft type ext4 (rw,relatime,errors=remount-ro,data=ordered)
/dev/sdb4 on /var/lib/lxd/devices/snapcraft-gallery-dl/disk.Source Tree of "gallery-dl - Command-line program to download image-galleries and -collections from several image hosting sites".home-ubuntu-gallery-dl type ext4 (rw,relatime,errors=remount-ro,data=ordered)
/dev/sdb4 on /var/lib/lxd/devices/snapcraft-gallery-dl/disk.Source Tree of "Unofficial Snap Packaging for gallery-dl".home-ubuntu-gallery-dl-snap type ext4 (rw,relatime,errors=remount-ro,data=ordered)
$ snap version
snap    2.37.2                                                             
snapd   2.37.2
series  16
ubuntu  18.04
kernel  4.15.0-45-generic