After a recent upgrade of a Ubuntu xenial machine, a particular autofs multi-map mount setup stopped working. A simplified example is:
:::::::::::::: auto.master :::::::::::::: /net /etc/auto.net :::::::::::::: auto.net :::::::::::::: localhost / :/ /loc :/loc Accessing /net/localhost/loc should trigger two nested bind mounts on /net/localhost and /net/localhost/loc, but with the new kernel, it fails with ELOOP: $ ls /net/localhost/loc ls: cannot open directory '/net/localhost/loc': Too many levels of symbolic links The problem is related to the upgrade of the Ubuntu xenial kernel from 4.4.0-38.57 to 4.4.0-78.99. I bisected the regression to commit 731ac92843877f3633325203abc942193c1e9001, which is a Ubuntu backport of this upstream kernel commit: commit 1064f874abc0d05eeed8993815f584d847b72486 Author: Eric W. Biederman <[email protected]> Date: Fri Jan 20 18:28:35 2017 +1300 mnt: Tuck mounts under others instead of creating shadow/side mounts. -- Dick
