Hey Miklosz, hey Amir, We've been observing regressions in our containers test-suite with commit: Author: Miklos Szeredi <mszeredi@xxxxxxxxxx> Date: Tue Mar 17 15:04:22 2020 +0100 ovl: separate detection of remote upper layer from stacked overlay Following patch will allow remote as upper layer, but not overlay stacked on upper layer. Separate the two concepts. This patch is doesn't change behavior. Signed-off-by: Miklos Szeredi <mszeredi@xxxxxxxxxx> It suddenly consistently reports: [2422.695340] overlayfs: filesystem on '/home/lxcunpriv/.local/share/lxc/c2/overlay/delta' not supported as upperdir in dmesg where it used to work fine for basically 6 years when we added that test. The test creates a container c2 that uses the rootfs of another container c1 (normal directory on an ext4 filesystem). Here you can see the full mount options: Invalid argument - Failed to mount "/home/lxcunpriv/.local/share/lxc/c1/rootfs" on "/usr/lib/x86_64-linux-gnu/lxc" with options "upperdir=/home/lxcunpriv/.local/share/lxc/c2/overlay/delta,lowerdir=/home/lxcunpriv/.local/share/lxc/c1/rootfs,workdir=/home/lxcunpriv/.local/share/lxc/c2/overlay/work" Thanks! Christian