[Bug 1233610] Re: boot process hangs very often when NFS shares are used

[Steve Langasek]

So here's what we know now:
 - the reason I've not been able to reproduce this problem is because my mounts are listed by name, and are *not* resolvable before the network is up; so the mount helper fails immediately with an unresolvable name (since mount correctly detects the network is down, and propagates this failure up the stack).  In the submitter's case, the name *is* resolvable (via /etc/hosts) before the network is up, which means that the mount helper gets an IP to pass down to the kernel, which it does... and the kernel's behavior in response to a mount request for an unreachable IP is less than stellar (to wit: it does *not* immediately return an error).
 - even after sorting out this problem, the latest boot logs still show a problem getting all the way through the mounts.  The mounts all succeed and are reported back, but the 'mounted' events don't finish for all of these, either because something in upstart is blocking them or because they get lost along the way in mountall.

My current theory as to why the mounted events are being lost is because
of a known issue with SIGUSR1 triggering duplicate 'mounting' events
(bug #1048017)... perhaps if one of these 'mounting' events is being
triggered late for the mount (which appears to be the case, from the
logs), it is blocking the 'mounted' event from happening correctly.
This is supported by the fact that the logs show an extra 'mounting'
event for the mounts that aren't correctly recorded, vs. the ones that
are correctly recorded.

Of further note, in the latest log we're getting 3/8 remote mounts
recorded.  But two of these are actually events for the *same*
mountpoint.  I've seen this issue previously but don't have a bug report
open for it; it's certainly not the cause of boot hangs, but it could
cause mountall to emit the 'filesystem' event too early.

-- 
You received this bug notification because you are a member of Ubuntu
Foundations Bugs, which is subscribed to mountall in Ubuntu.
https://bugs.launchpad.net/bugs/1233610

Title:
  boot process hangs very often when NFS shares are used

Status in “mountall” package in Ubuntu:
  New

Bug description:
  I'm running up-to-date Ubuntu 12.04.3 with the 3.2 kernel. I have a
  FreeNAS box exporting a number of NFS shares. My machine can boot
  once-in-a-while but I have problems on practically every boot, that I
  need to resolve by rebooting and trying again.

  My fstab:

  # /etc/fstab: static file system information.
  proc            /proc           proc    nodev,noexec,nosuid 0       0
  UUID=2f6ca502-9419-4040-a702-2c9dc716dbc5 /               ext4    errors=remount-ro 0       1
  nodev /ramdisk tmpfs defaults 0 0
  silverbox:/mnt/vol1/software /nas/software nfs auto 0 0 # ENROLL
  silverbox:/mnt/vol1/videos /nas/videos nfs auto 0 0 # ENROLL
  silverbox:/mnt/vol4/backup /nas/backup nfs auto 0 0 # ENROLL
  silverbox:/mnt/vol4/home /home nfs auto,exec 0 0 # ENROLL
  silverbox:/mnt/vol4/source /home/zyga/source nfs auto 0 0 # ENROLL
  silverbox:/mnt/vol4/steam /nas/steam nfs auto,bootwait 0 0 # ENROLL
  silverbox:/mnt/vol4/music /nas/music nfs auto,bootwait 0 0 # ENROLL
  silverbox:/mnt/vol4/photos /nas/photos nfs auto,bootwait 0 0 # ENROLL

  The network between the two boxes is working perfectly over gigabit
  wired connection. I can always mount each share explicitly, it only
  causes failures a boot. My local network uses openwrt routers and has
  correct DNS setup for each machine.

  My desktop (the machine affected by this bug) uses network manager
  with DHCP connection but I did try static IP before and it had no
  effect on the failure rate.

  I've added a way to open an emergency tty (patched /etc/init/tty6.conf
  to start on startup) and inspected mountall logs (patched
  mountall.conf to have --debug, not have --verbose, have console log
  and not 'expect daemon'). I'll attach /var/log/mountall.log from a
  successful boot below.

  I have tried to debug this issue with jodh and xnox on #ubuntu-devel
  and got asked to report this and wait for slangasek. I can freely
  reproduce this bug and I can assist in debugging if required.

To manage notifications about this bug go to:
https://bugs.launchpad.net/ubuntu/+source/mountall/+bug/1233610/+subscriptions