Dick Streefland <d...@streefland.net> writes: > 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 <ebied...@xmission.com> > Date: Fri Jan 20 18:28:35 2017 +1300 > > mnt: Tuck mounts under others instead of creating shadow/side mounts.
I don't believe this is a kernel change. I dug up an old VM and I was able to reproduce this issue simply by installing autofs, and your auto.master and auto.net files. # uname -a Linux ubuntu-16 4.4.0-24-generic #43-Ubuntu SMP Wed Jun 8 19:27:37 UTC 2016 x86_64 x86_64 x86_64 GNU/Linux # ls /net/ localhost # ls /net/localhost/loc ls: cannot open directory '/net/localhost/loc': Too many levels of symbolic links # ls /loc ls: cannot open directory '/loc/': Too many levels of symbolic links I suspect there is configuration somewhere in your autofs configuration. I don't speak autofs well enough to debug the issue at this point. But I can conclusively say it was not the kernel commit you pointed at, as I see the issue you are reporting and I don't have that commit in the kernel under test. Eric