Test on Trusty Before: $ uname -a Linux bionic 3.13.0-155-generic #205-Ubuntu SMP Fri Aug 10 15:53:26 UTC 2018 x86_64 x86_64 x86_64 GNU/Linux $ echo 9 | sudo tee /proc/sys/kernel/printk 9 $ sudo losetup --find --show --partscan rlv_grkgld.1mb [ 270.506420] partition (null) (3 pp's found) is not contiguous [ 270.510221] partition (null) (1 pp's found) is not contiguous [ 270.513952] partition (null) (68 pp's found) is not contiguous ... [ 270.593589] partition (null) (3 pp's found) is not contiguous [ 270.595603] partition (null) (2 pp's found) is not contiguous [ 270.597428] BUG: unable to handle kernel paging request at 0000000000001000 [ 270.599525] IP: [] strnlen+0xd/0x40 [ 270.601404] PGD 0 [ 270.601404] Oops: 0000 [#1] SMP [ 270.601404] Modules linked in: squashfs isofs nls_iso8859_1 kvm_intel kvm serio_raw sch_fq_codel iscsi _tcp libiscsi_tcp libiscsi scsi_transport_iscsi ip_tables x_tables autofs4 btrfs libcrc32c raid10 raid456 async_memcpy async_raid6_recov async_pq async_xor async_tx xor raid6_pq raid1 raid0 multipath linear psm ouse floppy [ 270.601404] CPU: 1 PID: 972 Comm: losetup Not tainted 3.13.0-155-generic #205-Ubuntu [ 270.601404] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.10.2-1ubuntu1 04/01/2014 [ 270.601404] task: ffff88003998e000 ti: ffff88003b1b6000 task.ti: ffff88003b1b6000 [ 270.601404] RIP: 0010:[] [] strnlen+0xd/0x40 [ 270.601404] RSP: 0018:ffff88003b1b7888 EFLAGS: 00010086 [ 270.601404] RAX: ffffffff81a674a1 RBX: ffffffff81ecbdec RCX: fffffffffffffffe [ 270.601404] RDX: 0000000000001000 RSI: ffffffffffffffff RDI: 0000000000001000 [ 270.601404] RBP: ffff88003b1b7888 R08: 000000000000ffff R09: 000000000000ffff [ 270.601404] R10: ffffffff813e27f0 R11: ffff88003b1b773e R12: 0000000000001000 [ 270.601404] R13: ffffffff81ecc1c0 R14: 00000000ffffffff R15: 0000000000000000 [ 270.601404] FS: 00007fbcbba18740(0000) GS:ffff88003ee80000(0000) knlGS:0000000000000000 [ 270.601404] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 270.601404] CR2: 0000000000001000 CR3: 000000003a9fe000 CR4: 0000000000000670 [ 270.601404] Stack: [ 270.601404] ffff88003b1b78c0 ffffffff8137c0ab ffffffff81ecbdec ffffffff81ecc1c0 [ 270.601404] ffff88003b1b79c0 ffffffff81a939c6 ffffffff81a939c6 ffff88003b1b7928 [ 270.601404] ffffffff8137d521 0000000000000086 ffff88003b1b773e 000000000000000c [ 270.601404] Call Trace: [ 270.601404] [] string.isra.5+0x3b/0xf0 [ 270.601404] [] vsnprintf+0x1c1/0x610 [ 270.601404] [] vscnprintf+0xd/0x30 [ 270.601404] [] vprintk_emit+0x111/0x530 [ 270.601404] [] printk+0x67/0x69 [ 270.601404] [] aix_partition+0x613/0x620 [ 270.601404] [] ? radix_tree_lookup_slot+0xe/0x10 [ 270.601404] [] msdos_partition+0x870/0x890 [ 270.601404] [] ? read_cache_page+0x21/0x30 [ 270.601404] [] ? read_dev_sector+0x2d/0x90 [ 270.601404] [] ? snprintf+0x39/0x40 [ 270.601404] [] ? parse_solaris_x86+0x230/0x230 [ 270.601404] [] check_partition+0x10a/0x240 [ 270.601404] [] rescan_partitions+0xb7/0x2c0 [ 270.601404] [] blkdev_ioctl+0xef/0x7d0 [ 270.601404] [] ? schedule_timeout+0x279/0x310 [ 270.601404] [] ioctl_by_bdev+0x33/0x40 [ 270.601404] [] loop_set_status+0x39a/0x3b0 [ 270.601404] [] loop_set_status64+0x50/0x70 [ 270.601404] [] lo_ioctl+0x1e8/0x730 [ 270.601404] [] blkdev_ioctl+0x21f/0x7d0 [ 270.601404] [] ? system_call_after_swapgs+0x156/0x170 [ 270.601404] [] block_ioctl+0x41/0x50 [ 270.601404] [] do_vfs_ioctl+0x2e3/0x4d0 [ 270.601404] [] ? system_call_after_swapgs+0x117/0x170 [ 270.601404] [] ? system_call_after_swapgs+0x110/0x170 [ 270.601404] [] ? system_call_after_swapgs+0x109/0x170 [ 270.601404] [] ? system_call_after_swapgs+0x102/0x170 [ 270.601404] [] ? system_call_after_swapgs+0xfb/0x170 [ 270.601404] [] ? system_call_after_swapgs+0xf4/0x170 [ 270.601404] [] ? system_call_after_swapgs+0xed/0x170 [ 270.601404] [] ? system_call_after_swapgs+0xe6/0x170 [ 270.601404] [] SyS_ioctl+0x81/0xa0 [ 270.601404] [] ? system_call_after_swapgs+0xb5/0x170 [ 270.601404] [] system_call_fastpath+0x1a/0x1f [ 270.601404] Code: c0 01 80 38 00 75 f7 48 29 f8 5d c3 31 c0 5d c3 66 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 55 48 85 f6 48 8d 4e ff 48 89 e5 74 2a <80> 3f 00 74 25 48 89 f8 31 d2 eb 10 0f 1f 80 00 00 00 00 48 83 [ 270.601404] RIP [] strnlen+0xd/0x40 [ 270.601404] RSP [ 270.601404] CR2: 0000000000001000 [ 270.732715] ---[ end trace c22abe83af8ab594 ]--- After: $ uname -a Linux bionic 3.13.0-155-generic #205+sf181954.1 SMP Wed Aug 15 17:05:33 -03 2018 x86_64 x86_64 x86_64 GNU/Linux $ echo 9 | sudo tee /proc/sys/kernel/printk 9 $ sudo losetup --find --show --partscan rlv_grkgld.1mb /dev/loop0