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Bug#748211: os-prober: Dangerous failure during kernel upgrade (probed NFS?)

Package: os-prober
Version: 1.58
Severity: normal

Dear Maintainer,
*** Please consider answering these questions, where appropriate ***

os-prober can appear to hang, possibly while trying to probe a hung NFS
server, and attempts to kill this (typically invoked during kernel
upgrade) can leave you with a machine which can't mount drives that it
needs to probe, because the kernel upgrade has removed/updated the
running kernel's FS modules.

I'm not sure what the best way of dealing with this is, but two that
occur to me are:

  - If os-prober hung because it was trying to probe my NFS mount, then
    should it really be doing that?  Does it make sense to os-probe
    network drives during a kernel upgrade?

  - If it hung because it was trying to load fuse/ntfs kernel modules
    which had just been rendered unloadable by updates from the (3.2.0-4
    to 3.2.0-4, so far as I can see: same version) partial kernel
    upgrade, then perhaps os-prober should be run before the existing
    kernel's modules are replaced?

Sequence of events:

  - I was performing a kernel upgrade as part of a typical "aptitude
    upgrade" command.  An NFS server that I usually mount (listed as
    "auto,_netdev" in /etc/fstab) had failed, so the just-booted system
    was, at a guess, still trying to mount it in the background,
    although I'd not noticed this at the time.

  - The grub configuration update appeared to hang.  No error messages,
    it just stopped part way through the list of installed OSes.  It
    found Linux but stopped before finding Windows.

  - After a while I killed the upgrade (suspend, kill %1), hoping to
    work out what was wrong and re-run the upgrade.  Subsequent attempts
    to run dpkg --configure -a, or aptitude reinstall <kernel> failed
    due to locked dpkg files.

  - lsof on the lock files wouldn't terminate.  I noticed the hung nfs
    mount process, killed that and then found and killed the tail of the
    os-probe process chain.  This allowed me to run dpkg --reconfigure
    and aptitude update/reinstall.

  - However by this stage my running kernel's modules had been
    obliterated by the upgrade, and os-prober couldn't load fuse.ko in
    order to probe the Windows 7 partitions (which aren't mounted by

  - This left me in the somewhat scary situation of knowing I had a
    partially upgraded kernel, no way of completing the upgrade, and not
    knowing whether I could safely reboot.

  - As it turned out, reboot worked and I could then run the reinstall

*** End of the template - remove these lines ***

-- System Information:
Debian Release: 7.5
  APT prefers stable
  APT policy: (500, 'stable')
Architecture: amd64 (x86_64)
Foreign Architectures: i386

Kernel: Linux 3.2.0-4-amd64 (SMP w/8 CPU cores)
Locale: LANG=en_GB.utf8, LC_CTYPE=en_GB.utf8 (charmap=UTF-8)
Shell: /bin/sh linked to /bin/dash

Versions of packages os-prober depends on:
ii  libc6  2.13-38+deb7u1

os-prober recommends no packages.

os-prober suggests no packages.

-- no debconf information

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