[xfs] Calltrace in 2.6.27 kernel

[Christoph Hellwig]

On Thu, Nov 13, 2008 at 03:22:58PM +0100, aluno3 at poczta.onet.pl wrote:
> Hi
> 
> I tested kernel 2.6.27 with stress test using fsstress,dd,LVM and
> snapshots. After a few hours and overflow of snapshot I got call trace:
> 
> device-mapper: snapshots: Invalidating snapshot: Unable to allocate
> exception.

This is a message from device mapper telling your that it got an EIO
in pending_complete()

> I/O error in filesystem ("dm-49") meta-data dev dm-49 block
> 0x1d4c3b0       ("xlog_recover_do..(read#2)")
>  error 5 buf count 8192
> XFS: log mount/recovery failed: error 5
> XFS: log mount failed

And now XFS complains that it got this error passed up, so far so good.

> BUG: unable to handle kernel NULL pointer dereference at 0000002c
> IP: [<c029553d>] xfs_log_force_umount+0x3d/0x170
> *pdpt = 00000000345cf001 *pde = 0000000000000000

But ut should not crash.  Can you run 

	addr2line -e /path/to/your/kernel xfs_log_force_umount+0x3d/0x170

(you'll need a kernel with debuginfo for that)