Hello, dm_io() does following: if (!io_req->notify.fn) So it expects caller to initialize notify.fn, but in couple of places it is not done when allocating on stack... dm-bufio.c:dm_bufio_issue_flush() dm-raid1.c:mirror_flush() chunk_io() does it correctly... struct dm_io_request io_req = { ...., .notify.fn = NULL, }; I wonder how raid and buf io then works. By chance... - Dmitry -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel