[systemd-devel] dev-root.device is not active, results in an umount spree

Lennart Poettering lennart at poettering.net
Wed May 13 05:43:49 PDT 2015


On Wed, 13.05.15 12:48, Dimitri John Ledkov (dimitri.j.ledkov at intel.com) wrote:

> I am booting without initramfs, using a plan9 filesystem as rootfs in a kvm.
> 
> Thus my /proc/cmdline has:
> root=/dev/root rootflags=rw,trans=virtio,version=9p2000.L rootfstype=9p
> 
> # mount
> /dev/root on / type 9p
> (rw,relatime,sync,dirsync,rw,trans=virtio,version=9p2000.L)
> 
> Yet, dev-root.device is dead:
> # systemctl status dev-root.device
> ‚óŹ dev-root.device
>    Loaded: loaded
>    Active: inactive (dead)

Yeah, this /dev/root thing is really weird in the kernel. It's not an
actual device, it's just a weird string. We probably should filter it
out entirely, and never ever generate a unit dependency for it.

Please check if this fixes things for you:

http://cgit.freedesktop.org/systemd/systemd/commit/?id=7ba2711d3fd283c389db2a1e7b9598ba9f0dac0c

That said, I figure you should backport
628c89cc68ab96fce2de7ebba5933725d147aecc and friends to your tree,
which should also make this problem go away for you.

> I am planning to locally patch mount_add_device_links to skip if what
> is "/dev/root", to avoid a call to unit_add_node_link... But I'm not
> sure if this is the right thing to do or not.

It is, it's the change I made now, too.

Lennart

-- 
Lennart Poettering, Red Hat


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