VirtualBox shared folder hang with 3.11 kernel

[Mike Kupfer <m.kupfer@acm.org>]

I have a 64-bit guest running Jessie; the host is running Wheezy.  AMD
processor, in case that's relevant.

With the 3.11-2 kernel, "df -h" of a shared folder produces more or less
the expected results:

  Host:
    $ df -h $HOME
    Filesystem      Size  Used Avail Use% Mounted on
    /dev/sda5       409G   73G  315G  19% /home
  
  Guest:
    $ df -h /media/sf_VirtualBoxShare/
    Filesystem      Size  Used Avail Use% Mounted on
    none            409G   94G  315G  23% /media/sf_VirtualBoxShare

But ls hangs

  $ ls /media/sf_VirtualBoxShare/

strace shows it doing 

  getdents(3, /* 1 entries */, 32768)     = 24

over and over.

(FWIW, the host says the directory is empty.)

I don't recall having this problem with the 3.10-3 kernel.

I'm using Debian's VirtualBox packages, not the ones from Oracle (though
they had been installed at one time).

Thanks for any clues,

mike