Comment 12 for bug 768506

Mike Perrin (mperrin) wrote :

It turns out that my three previous posts have been about half right. After further research and testing I have concluded that:
- This is a zombie bug. I recommend this bug be marked as yet another in the long list of duplicate bugs for #211631.
- Sander Marechal's umountcifs is not needed for a workaround.
- The root cause is that Network Manager, controlled by upstart, terminates early and disables the network interfaces before the cifs shares are unmounted. To validate this, I disabled network manager and manually brought up my wireless interface using iwconfig and ifconfig. With two shares mounted a normal shutdown was achieved on ten successive trials.
- Comment #139 in bug #211631 notes that Linux Mint 10 does not have this problem by virtue of relinking umountnfs to K15umountnfs in rc0.d and rc6.d. I validated this by achieving ten successive normal shutdowns with two shares mounted and my wireless connection controlled by Network Manager. (Note that Glen Robinson's comment #139 says umountnfs was originally linked as S43umountnfs whereas my 11.04 installation had linked as I am unable to explain the discrepancy.) Glen also states that he did not have the problem with a hardwire network, as I reported in comment #7 above.
- Since this is a race (timing) problem, there is no guarantee that either of the above two workarounds would be effective for all situations.
- My cifs management script was interfering with shutdown, confusing my investigation of the original problem . I think I have that fixed now. How unusual - a bug in my code!