I think this is a race in ccw_io_helper(). The stress-ng sysfs stressor is running multiple threaded reads of /sys/devices/css0/0.0.0000/0.0.0000/virtio0/block/vda/cache_type which results in reads via virtio_cread8() and ultimately reads using virtio_ccw_get_config()
I added debug into virtio_cread8 and it returns 1 99% of the time, and sometimes in a threaded read we get it returning garbage, such as 200 in the following trace: [ 39.767777] virtio_cread8 32 -> 1 [ 39.767933] virtio_cread8 32 -> 1 [ 39.787712] virtio_cread8 32 -> 200 [ 39.787810] kernel BUG at drivers/block/virtio_blk.c:576! -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1788432 Title: 4.15 s390x kernel BUG at /build/linux- Gycr4Z/linux-4.15.0/drivers/block/virtio_blk.c:565! To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/1788432/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
