Hi Christoph, Jens, I found an interesting bug in my KVM guest (tested on s390x). The guest uses a virtio-scsi disk and the current linux-next kernel. The problem is that I cannot get the SCSI ID of the attached SCSI disk. Running the command `lsscsi --scsi_id` in the guest returns: root@qemus390x:~# lsscsi --scsi_id [0:0:0:0] disk Linux scsi_debug 0190 /dev/sda - but the expected result is something like: root@qemus390x:~# lsscsi --scsi_id [0:0:0:0] disk Linux scsi_debug 0190 /dev/sda 33333333000002710 Also there is no /dev/disk/by-id/scsi-* path created. I bisected the problem to... commit f3256075ba49d80835b601bfbff350a2140b2924 (HEAD, refs/bisect/bad) Author: Christoph Hellwig <hch@xxxxxx> Date: Thu Aug 27 17:37:45 2020 +0200 block: remove the BIO_NULL_MAPPED flag When I reverted this commit the problem was gone. Any ideas what the problem is? Thanks in advance. Best regards, Marc