Nfs mount hangs while automounting home

[Alex Bachmeier]

On my Ubuntu Precise nfs clients with autofs, the mount.nfs process hangs for hours until the autofs service is restarted.
I haven't been able to get an strace from this, since it doesn't happen all the time.
I do have a kernel log trace, since sshd was being blocked which resulted in a hung task.

The nfs server is running Ubuntu Lucid. This behavior did not happen with the previous 11.04 clients.

This bug might also be related to nfs-common.

Versions:
autofs5 5.0.6-0ubuntu4
nfs-common 1:1.2.5-3ubuntu1
linux-image-generic 3.2.0.19.21

[James Page (james-page)]

Hi Alex

Are you using nis as well?

[Alex Bachmeier (cebalrai)]

nfs3+ heimdal Kerberos for authentication + ldap

[Alex Bachmeier (cebalrai)]

This bug might actually be related to nfs-common, but I'm not sure yet.
I'm debugging the situation right now.
A workaround that might be working is setting the MOUNT_WAIT variable in /etc/default/autofs

nfs debugging didn't give me anything usefel yet, I will see what I can pick up with wireshark.

After the failed mount in the syslog, the "mount.nfs" process sits there with ~16%CPU.

[Alex Bachmeier (cebalrai)]

I believe I have narrowed down the bug to a race condition with the 10.04 sever and its exported nfs4 shares. The nfs client tries to mount the nfs4 shares and get caught in a loop. The workaround for this is forcing nfs3 in the auto.master using:
"/home /etc/autofs/auto.home vers=3,--timeout=120"

I'm marking the bug as invalid, since this is not a problem with autofs itself.