[CRIU] Restoring lxc-1.1.5 centos 7 container with httpd fails

[Andrey Vagin]

Hi Adrian,

Can you create a kvm VM where I will be able to reproduce the problem?

I tried to reproduce it by myself, but it works for me.

18435 pts/0    S      0:00 [lxc monitor] /var/lib/lxc centos
18441 ?        Ss     0:00  \_ /sbin/init
18475 ?        Ss     0:00      \_ /usr/lib/systemd/systemd-journald
18476 ?        Ss     0:00      \_ /usr/lib/systemd/systemd-udevd
18477 ?        Ss     0:00      \_ /usr/lib/systemd/systemd-logind
18478 ?        Ss     0:00      \_ /bin/dbus-daemon --system
--address=systemd: --nofork --nopidfile --systemd-activation
18479 ?        Ssl    0:00      \_ /usr/sbin/rsyslogd -n
18480 ?        Ss     0:00      \_ /usr/sbin/sshd -D
18481 ?        Ss     0:00      \_ /usr/sbin/httpd -DFOREGROUND
18482 ?        S      0:00          \_ /usr/sbin/httpd -DFOREGROUND
18483 ?        S      0:00          \_ /usr/sbin/httpd -DFOREGROUND
18484 ?        S      0:00          \_ /usr/sbin/httpd -DFOREGROUND
18485 ?        S      0:00          \_ /usr/sbin/httpd -DFOREGROUND
18486 ?        S      0:00          \_ /usr/sbin/httpd -DFOREGROUND
19812 ?        Ss     0:00 /usr/sbin/crond -n
[root at localhost lxc]# LD_LIBRARY_PATH=/usr/local/lib64/ ./src/lxc/lxc-checkpoint -s -n centos -D /root/images -v
[root at localhost lxc]# LD_LIBRARY_PATH=/usr/local/lib64/ ./src/lxc/lxc-checkpoint -r -n centos -D /root/images -v
[root at localhost lxc]# echo $?
0
[root at localhost lxc]# git describe HEAD
lxc-2.0.0


On Fri, May 06, 2016 at 10:25:12PM +0200, Adrian Reber wrote:
> > > > We've discussed with Adrian in irc and he promised to give more
> > > > info about this issue.
> > > > 
> > > > To investiage this sort of bugs I add sleep(1000) after pr_err() to
> > > > freeze processes in a moment of the error and try to find what is wrong
> > > > here via /proc/PID/root.
> > > 
> > > With the sleep after the last pr_err() I see two criu processes:
> > > 
> > > # ls -la /proc/10183/root
> > > lrwxrwxrwx. 1 root root 0 May  6 08:47 /proc/10183/root -> /
> > > # ls -la /proc/10188/root
> > > lrwxrwxrwx. 1 root root 0 May  6 08:47 /proc/10188/root -> /
> > 
> > I mean that you need to try to resolve source and target argumnets of a
> > mount syscall which returns an error.
> 
> I am not really sure what to do. The current restore fails with:
> 
> (00.080566)      1: mnt: 	Bind /tmp/cr-tmpfs.KD4sxa/hugetlb to .criu.mntns.07hSc4/13/sys/fs/cgroup/hugetlb
> (00.080585)      1: Error (mount.c:2479): mnt: Can't mount at .criu.mntns.07hSc4/13/sys/fs/cgroup/hugetlb: No such file or directory
> 
> The directory /proc/4745/root/var/lib/lxc/c7/rootfs/.criu.mntns.07hSc4
> is empty. So that seems to explain why the mount is not working.
> 
> The other directory exists:
> 
> # ls  /proc/4745/root/tmp/cr-tmpfs.KD4sxa/hugetlb/
> lxc
> 
> So is the first empty directory the problem? As the path contains
> 'mntns'... Does this need some special mount namespace support. This is
> running on the CentOS 7 kernel. Which might be missing some features.
> 
> 
> 		Adrian