[lxc-devel] Strange problem (stray mounts) with lxc-create...

[Michael H. Warfield]

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.

Any downside to doing that?

Regards,
Mike
-- 
Michael H. Warfield (AI4NB) | (770) 985-6132 |  mhw at WittsEnd.com
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