NULL mp->m_log in 2.6.31 xfs_log_move_tail

[Christoph Hellwig]

On Mon, Nov 09, 2009 at 03:39:32PM -0500, Ed Cashin wrote:
> A colleague has seen oopses in 2.6.31 when an XFS is mounted on an AoE
> target that becomes unresponsive and is marked as "down" by the aoe
> driver.  The aoe driver starts failing all new I/O requests after
> failing all current requests when the device is down.

And the oops happens when unmounting the devices?  That's at least how
the trace looks like.   If that's the case I suspect we tear down the
log a bit too early - I'll do an audit of the log shutdown path how this
could happen.