Luis,

Since commit 80c49563e250 ("scsi: scsi_debug: implement IMMED bit")
there are long delays in F_SYNC_DELAY and F_SSU_DELAY.  This can cause
a memory leak in schedule_resp(), which can be invoked while unloading
the scsi_debug module: free_all_queued() had already freed all sd_dp
and schedule_resp will alloc a new one, which will never get freed.
Here's the kmemleak report while running xfstests generic/350:

Applied to 4.18/scsi-fixes. Thank you!

-- 
Martin K. Petersen	Oracle Linux Engineering