On Sun, 2011-09-18 at 15:05 +0100, Chris Boot wrote: 

quoted

Hardly ... all it's saying is that twa_exit doesn't wait for pending I/O
to complete, so when you remove the module it tears down in the middle
of an I/O.  A bug, yes, but it's not indicative of any sort of leak in
the maps/unmaps.

James,

I don't think that's the case - I had unmounted all filesystems, deactivated all volume groups, and performed a sync before waiting a few seconds and running rmmod. Next time I'll also 'echo 1 > /sys/block/sdX/device/delete' if that's helpful.

Actually, I take all that back: the driver has a bug in QUEUE_FULL
handling: twa_scsi_queue() calls twa_scsiop_execute_scsi(), which maps
the dma buffer, but if the card responds QUEUE_FULL it just returns
SCSI_MLQUEUE_HOST_BUSY without ever unmapping.  That leg in the code
frees the request but also doesn't unmap it.  In fact any error return
from twa_scsiop_execute_scsi() seems to have the same problem (but
QUEUE_FULL is the only silent one).

I trust Adam will fix this.

James