[lxc-devel] Strange problem (stray mounts) with lxc-create...
Serge Hallyn
serge.hallyn at ubuntu.com
Wed Oct 9 15:10:34 UTC 2013
Quoting Michael H. Warfield (mhw at WittsEnd.com):
> On Wed, 2013-10-09 at 09:50 -0500, Serge Hallyn wrote:
> > > lxc-create -n Ubuntu-test -t ubuntu
> > >
> > > Bingo...
> > >
> > > /dev/mapper/fedora-root on /usr/lib64/lxc/rootfs type ext4 (rw,relatime,seclabel,data=ordered)
> > >
> > > Why is lxc-create even creating that mount? I don't see any reason for
> >
> > Check lxccontainer.c:785 and line 805. We call bdev_mount() in case its
> > a blockdev. In the case of a dir-backed container we still end up doing
> > a bind mount of the rootfs.
> >
> > > it. We're never running the container in lxc-create. Running
> > > "umount /usr/lib64/lxc/rootfs" clears it and we're off to the races
> > > again.
> > >
> > > If I were to venture a WAG (Wild Ass Guess) some initialization code is
> > > creating that bind mount that is not needed and that the cleanup code in
> > > lxc-create is unaware of. But I haven't gone to the trouble of trying
> > > to track the code down yet.
>
> > Now is your / still MS_SHARED? The bdev create and templates
> > run in a private namespace, but if MS_SHARED then the mounts get
> > bounced back to host. Maybe we need to manually set MS_PRIVATE every
> > time after doing an unshare() in lxc code.
>
> It doesn't seem to be... Am I looking in the right spot. I don't see
> it in the options...
>
> [root at hydra mhw]# mount | grep ' / '
> /dev/mapper/fedora-root on / type ext4 (rw,relatime,seclabel,data=ordered)
What does /proc/self/mountinfo on the host looks like?
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