Bug 1396309

Summary: Prevent activation of RAID10 with kernels not supporting proper mapping
Product: Red Hat Enterprise Linux 7 Reporter: Corey Marthaler <cmarthal>
Component: lvm2Assignee: Heinz Mauelshagen <heinzm>
lvm2 sub component: Mirroring and RAID QA Contact: cluster-qe <cluster-qe>
Status: CLOSED NOTABUG Docs Contact:
Severity: urgent    
Priority: unspecified CC: agk, heinzm, jbrassow, msnitzer, prajnoha, prockai, rbednar, zkabelac
Version: 7.3   
Target Milestone: rc   
Target Release: ---   
Hardware: x86_64   
OS: Linux   
Whiteboard:
Fixed In Version: lvm2-2.02.169-1.el7 Doc Type: If docs needed, set a value
Doc Text:
Story Points: ---
Clone Of:
: 1463740 (view as bug list) Environment:
Last Closed: 2017-06-21 15:47:57 UTC Type: Bug
Regression: --- Mount Type: ---
Documentation: --- CRM:
Verified Versions: Category: ---
oVirt Team: --- RHEL 7.3 requirements from Atomic Host:
Cloudforms Team: --- Target Upstream Version:
Embargoed:
Bug Depends On:    
Bug Blocks: 1463740    

Description Corey Marthaler 2016-11-17 23:54:02 UTC 
Description of problem:
This is the raid10 specific version of bug 1388962.

## Shared storage 7.2 machine 3.10.0-327.el7, lvm2-2.02.130-5.el7
[root@host-088 ~]# dmsetup targets|grep raid
raid             v1.7.0

[root@host-088 ~]# lvcreate -i 3 --type raid10 -n raid10 -L 100M VG
  Using default stripesize 64.00 KiB.
  Rounding size (25 extents) up to stripe boundary size (27 extents).
  Logical volume "raid10" created.
[root@host-088 ~]# lvs -a -o +devices
  LV                VG  Attr       LSize   Cpy%Sync Devices
  raid10            VG  rwi-a-r--- 108.00m 100.00   raid10_rimage_0(0),raid10_rimage_1(0),raid10_rimage_2(0),raid10_rimage_3(0),raid10_rimage_4(0),raid10_rimage_5(0)
  [raid10_rimage_0] VG  iwi-aor---  36.00m          /dev/sda1(1)
  [raid10_rimage_1] VG  iwi-aor---  36.00m          /dev/sdb1(1)
  [raid10_rimage_2] VG  iwi-aor---  36.00m          /dev/sdc1(1)
  [raid10_rimage_3] VG  iwi-aor---  36.00m          /dev/sdd1(1)
  [raid10_rimage_4] VG  iwi-aor---  36.00m          /dev/sde1(1)
  [raid10_rimage_5] VG  iwi-aor---  36.00m          /dev/sdf1(1)
  [raid10_rmeta_0]  VG  ewi-aor---   4.00m          /dev/sda1(0)
  [raid10_rmeta_1]  VG  ewi-aor---   4.00m          /dev/sdb1(0)
  [raid10_rmeta_2]  VG  ewi-aor---   4.00m          /dev/sdc1(0)
  [raid10_rmeta_3]  VG  ewi-aor---   4.00m          /dev/sdd1(0)
  [raid10_rmeta_4]  VG  ewi-aor---   4.00m          /dev/sde1(0)
  [raid10_rmeta_5]  VG  ewi-aor---   4.00m          /dev/sdf1(0)

[root@host-088 ~]# vgchange -an VG
  0 logical volume(s) in volume group "VG" now active


## Shared storage 7.3 machine W/ the lvm fix for bug 1395563 3.10.0-514.el7 lvm2-2.02.166-1.el7_3.2
[root@host-090 ~]# dmsetup targets|grep raid
raid             v1.9.0

[root@host-090 ~]# pvscan --cache
[root@host-090 ~]# lvs -a -o +devices
  LV                VG  Attr       LSize    Devices
  raid10            VG  rwi---r--- 108.00m  raid10_rimage_0(0),raid10_rimage_1(0),raid10_rimage_2(0),raid10_rimage_3(0),raid10_rimage_4(0),raid10_rimage_5(0)
  [raid10_rimage_0] VG  Iwi---r---  36.00m  /dev/sdb1(1)
  [raid10_rimage_1] VG  Iwi---r---  36.00m  /dev/sde1(1)
  [raid10_rimage_2] VG  Iwi---r---  36.00m  /dev/sda1(1)
  [raid10_rimage_3] VG  Iwi---r---  36.00m  /dev/sdd1(1)
  [raid10_rimage_4] VG  Iwi---r---  36.00m  /dev/sdc1(1)
  [raid10_rimage_5] VG  Iwi---r---  36.00m  /dev/sdf1(1)
  [raid10_rmeta_0]  VG  ewi---r---   4.00m  /dev/sdb1(0)
  [raid10_rmeta_1]  VG  ewi---r---   4.00m  /dev/sde1(0)
  [raid10_rmeta_2]  VG  ewi---r---   4.00m  /dev/sda1(0)
  [raid10_rmeta_3]  VG  ewi---r---   4.00m  /dev/sdd1(0)
  [raid10_rmeta_4]  VG  ewi---r---   4.00m  /dev/sdc1(0)
  [raid10_rmeta_5]  VG  ewi---r---   4.00m  /dev/sdf1(0)

[root@host-090 ~]# lvchange -ay VG/raid10
  device-mapper: reload ioctl on (253:14) failed: Invalid argument

Nov 17 17:49:00 host-090 kernel: device-mapper: raid: Reshaping raid sets not yet supported. (raid layout change)
Nov 17 17:49:00 host-090 kernel: device-mapper: raid: #011 0x102 vs 0x0
Nov 17 17:49:00 host-090 kernel: device-mapper: raid: #011 Old layout: near w/ 2 copies
Nov 17 17:49:00 host-090 kernel: ------------[ cut here ]------------
Nov 17 17:49:00 host-090 kernel: WARNING: at drivers/md/dm-raid.c:508 raid10_md_layout_to_format+0x50/0x60 [dm_raid]()
Nov 17 17:49:00 host-090 kernel: Modules linked in: dm_raid raid456 async_raid6_recov async_memcpy async_pq raid6_pq async_xor xor async_tx sd_mod crc_t10dif crct10dif_generic crct10dif_common sg iscsi_tcp libiscsi_tcp libiscsi scsi_transport_iscsi iptable_filter ppdev pcspkr i6300esb virtio_balloon parport_pc parport i2c_piix4 i2c_core dm_multipath nfsd auth_rpcgss nfs_acl lockd grace sunrpc ip_tables xfs libcrc32c ata_generic pata_acpi virtio_blk virtio_net ata_piix serio_raw libata virtio_pci virtio_ring virtio floppy dm_mirror dm_region_hash dm_log dm_mod
Nov 17 17:49:00 host-090 kernel: CPU: 0 PID: 2982 Comm: lvchange Not tainted 3.10.0-514.el7.x86_64 #1
Nov 17 17:49:00 host-090 kernel: Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2007
Nov 17 17:49:00 host-090 kernel: 0000000000000000 00000000efc84f1e ffff88003d573ab8 ffffffff81685eac
Nov 17 17:49:00 host-090 kernel: ffff88003d573af0 ffffffff81085820 0000000000000000 ffff88002e600498
Nov 17 17:49:00 host-090 kernel: ffff88002e600000 ffff88003b877000 0000000000000000 ffff88003d573b00
Nov 17 17:49:00 host-090 kernel: Call Trace:
Nov 17 17:49:00 host-090 kernel: [<ffffffff81685eac>] dump_stack+0x19/0x1b
Nov 17 17:49:00 host-090 kernel: [<ffffffff81085820>] warn_slowpath_common+0x70/0xb0
Nov 17 17:49:00 host-090 kernel: [<ffffffff8108596a>] warn_slowpath_null+0x1a/0x20
Nov 17 17:49:00 host-090 kernel: [<ffffffffa03b8c20>] raid10_md_layout_to_format+0x50/0x60 [dm_raid]
Nov 17 17:49:00 host-090 kernel: [<ffffffffa03b98fe>] super_validate.part.26+0x78e/0x7b0 [dm_raid]
Nov 17 17:49:00 host-090 kernel: [<ffffffff81237edd>] ? bio_put+0x7d/0xa0
Nov 17 17:49:00 host-090 kernel: [<ffffffff814fc62c>] ? sync_page_io+0x8c/0x110
Nov 17 17:49:00 host-090 kernel: [<ffffffffa03bb371>] raid_ctr+0xd41/0x1680 [dm_raid]
Nov 17 17:49:00 host-090 kernel: [<ffffffffa00050c1>] ? realloc_argv+0x31/0x80 [dm_mod]
Nov 17 17:49:00 host-090 kernel: [<ffffffffa00056f7>] dm_table_add_target+0x177/0x460 [dm_mod]
Nov 17 17:49:00 host-090 kernel: [<ffffffffa0008e37>] table_load+0x157/0x390 [dm_mod]
Nov 17 17:49:00 host-090 kernel: [<ffffffffa0008ce0>] ? retrieve_status+0x1c0/0x1c0 [dm_mod]
Nov 17 17:49:00 host-090 kernel: [<ffffffffa0009a35>] ctl_ioctl+0x1e5/0x500 [dm_mod]
Nov 17 17:49:00 host-090 kernel: [<ffffffffa0009d63>] dm_ctl_ioctl+0x13/0x20 [dm_mod]
Nov 17 17:49:00 host-090 kernel: [<ffffffff81211ed5>] do_vfs_ioctl+0x2d5/0x4b0
Nov 17 17:49:00 host-090 kernel: [<ffffffff812aea5e>] ? file_has_perm+0xae/0xc0
Nov 17 17:49:00 host-090 kernel: [<ffffffff81292e01>] ? unmerge_queues+0x61/0x70
Nov 17 17:49:00 host-090 kernel: [<ffffffff81212151>] SyS_ioctl+0xa1/0xc0
Nov 17 17:49:00 host-090 kernel: [<ffffffff816964c9>] system_call_fastpath+0x16/0x1b
Nov 17 17:49:00 host-090 kernel: ---[ end trace be565ba4c2478c63 ]---
Nov 17 17:49:00 host-090 kernel: device-mapper: raid: #011 New layout: far w/ 0 copies
Nov 17 17:49:00 host-090 kernel: device-mapper: table: 253:14: raid: Unable to assemble array: Invalid superblocks
Nov 17 17:49:00 host-090 kernel: device-mapper: ioctl: error adding target to table


Version-Release number of selected component (if applicable):
3.10.0-514.el7.x86_64

lvm2-2.02.166-1.el7_3.2    BUILT: Wed Nov 16 04:11:32 CST 2016
lvm2-libs-2.02.166-1.el7_3.2    BUILT: Wed Nov 16 04:11:32 CST 2016
lvm2-cluster-2.02.166-1.el7_3.2    BUILT: Wed Nov 16 04:11:32 CST 2016
device-mapper-1.02.135-1.el7_3.2    BUILT: Wed Nov 16 04:11:32 CST 2016
device-mapper-libs-1.02.135-1.el7_3.2    BUILT: Wed Nov 16 04:11:32 CST 2016
device-mapper-event-1.02.135-1.el7_3.2    BUILT: Wed Nov 16 04:11:32 CST 2016
device-mapper-event-libs-1.02.135-1.el7_3.2    BUILT: Wed Nov 16 04:11:32 CST 2016
device-mapper-persistent-data-0.6.3-1.el7    BUILT: Fri Jul 22 05:29:13 CDT 2016
cmirror-2.02.166-1.el7_3.2    BUILT: Wed Nov 16 04:11:32 CST 2016
sanlock-3.4.0-1.el7    BUILT: Fri Jun 10 11:41:03 CDT 2016
sanlock-lib-3.4.0-1.el7    BUILT: Fri Jun 10 11:41:03 CDT 2016
lvm2-lockd-2.02.166-1.el7_3.2    BUILT: Wed Nov 16 04:11:32 CST 2016


How reproducible:
Everytime
Comment 3 Heinz Mauelshagen 2017-03-08 13:09:01 UTC 
Upsream commit e118b65d651d
Comment 5 Roman Bednář 2017-05-16 13:24:34 UTC 
The patch does not seem to fix the problem. I was able to verify raid4 version of basically the same bug ( BZ #1388962 ) but not raid10 using the same procedure.

=============================================

Initial packages (RHEL7.2):
	3.10.0-327.el7.x86_64
	lvm2-2.02.130-5.el7.x86_64

# dmsetup targets|grep raid
raid             v1.7.0


# lvs -a -o lv_name,segtype,devices -S vg_name=vg
  LV                Type   Devices                                                                                                                                                                                      
  raid10            raid10 raid10_rimage_0(0),raid10_rimage_1(0),raid10_rimage_2(0),raid10_rimage_3(0),raid10_rimage_4(0),raid10_rimage_5(0),raid10_rimage_6(0),raid10_rimage_7(0),raid10_rimage_8(0),raid10_rimage_9(0)
  [raid10_rimage_0] linear /dev/sdi(1)                                                                                                                                                                                  
  [raid10_rimage_1] linear /dev/sdg(1)                                                                                                                                                                                  
  [raid10_rimage_2] linear /dev/sdf(1)                                                                                                                                                                                  
  [raid10_rimage_3] linear /dev/sdb(1)                                                                                                                                                                                  
  [raid10_rimage_4] linear /dev/sdh(1)                                                                                                                                                                                  
  [raid10_rimage_5] linear /dev/sda(1)                                                                                                                                                                                  
  [raid10_rimage_6] linear /dev/sdc(1)                                                                                                                                                                                  
  [raid10_rimage_7] linear /dev/sdd(1)                                                                                                                                                                                  
  [raid10_rimage_8] linear /dev/sde(1)                                                                                                                                                                                  
  [raid10_rimage_9] linear /dev/sdj(1)                                                                                                                                                                                  
  [raid10_rmeta_0]  linear /dev/sdi(0)                                                                                                                                                                                  
  [raid10_rmeta_1]  linear /dev/sdg(0)                                                                                                                                                                                  
  [raid10_rmeta_2]  linear /dev/sdf(0)                                                                                                                                                                                  
  [raid10_rmeta_3]  linear /dev/sdb(0)                                                                                                                                                                                  
  [raid10_rmeta_4]  linear /dev/sdh(0)                                                                                                                                                                                  
  [raid10_rmeta_5]  linear /dev/sda(0)                                                                                                                                                                                  
  [raid10_rmeta_6]  linear /dev/sdc(0)                                                                                                                                                                                  
  [raid10_rmeta_7]  linear /dev/sdd(0)                                                                                                                                                                                  
  [raid10_rmeta_8]  linear /dev/sde(0)                                                                                                                                                                                  
  [raid10_rmeta_9]  linear /dev/sdj(0)  

# vgchange -an vg

BEFORE PATCH:
Upgrade to 3.10.0-514.el7 and lvm2-2.02.166-1.el7

# dmsetup targets|grep raid
raid             v1.9.0

# pvscan --cache

# pvscan
  PV /dev/vda2   VG rhel_virt-369   lvm2 [7.51 GiB / 40.00 MiB free]
  PV /dev/sdi    VG vg              lvm2 [39.99 GiB / 39.79 GiB free]
  PV /dev/sdg    VG vg              lvm2 [39.99 GiB / 39.79 GiB free]
  PV /dev/sdf    VG vg              lvm2 [39.99 GiB / 39.79 GiB free]
  PV /dev/sdb    VG vg              lvm2 [39.99 GiB / 39.79 GiB free]
  PV /dev/sdh    VG vg              lvm2 [39.99 GiB / 39.79 GiB free]
  PV /dev/sda    VG vg              lvm2 [39.99 GiB / 39.79 GiB free]
  PV /dev/sdc    VG vg              lvm2 [39.99 GiB / 39.79 GiB free]
  PV /dev/sdd    VG vg              lvm2 [39.99 GiB / 39.79 GiB free]
  PV /dev/sde    VG vg              lvm2 [39.99 GiB / 39.79 GiB free]
  PV /dev/sdj    VG vg              lvm2 [39.99 GiB / 39.79 GiB free]
  Total: 11 [407.43 GiB] / in use: 11 [407.43 GiB] / in no VG: 0 [0   ]


# lvchange -ay vg/raid10
  device-mapper: reload ioctl on (253:22) failed: Invalid argument


May 16 14:58:45 virt-369 kernel: device-mapper: raid: #011 New layout: far w/ 0 copies
May 16 14:58:45 virt-369 kernel: device-mapper: table: 253:22: raid: Unable to assemble array: Invalid superblocks
May 16 14:58:45 virt-369 kernel: device-mapper: ioctl: error adding target to table
May 16 14:58:45 virt-369 multipathd: dm-22: remove map (uevent)
May 16 14:58:45 virt-369 multipathd: dm-22: remove map (uevent)


AFTER PATCH:
Upgrade to lvm2-2.02.171-1.el7.x86_64

# dmsetup targets|grep raid
raid             v1.9.0

# uname -r
3.10.0-514.el7.x86_64

# pvscan --cache

# pvscan
  PV /dev/sdi    VG vg              lvm2 [39.99 GiB / 39.79 GiB free]
  PV /dev/sdg    VG vg              lvm2 [39.99 GiB / 39.79 GiB free]
  PV /dev/sdf    VG vg              lvm2 [39.99 GiB / 39.79 GiB free]
  PV /dev/sdb    VG vg              lvm2 [39.99 GiB / 39.79 GiB free]
  PV /dev/sdh    VG vg              lvm2 [39.99 GiB / 39.79 GiB free]
  PV /dev/sda    VG vg              lvm2 [39.99 GiB / 39.79 GiB free]
  PV /dev/sdc    VG vg              lvm2 [39.99 GiB / 39.79 GiB free]
  PV /dev/sdd    VG vg              lvm2 [39.99 GiB / 39.79 GiB free]
  PV /dev/sde    VG vg              lvm2 [39.99 GiB / 39.79 GiB free]
  PV /dev/sdj    VG vg              lvm2 [39.99 GiB / 39.79 GiB free]
  PV /dev/vda2   VG rhel_virt-369   lvm2 [7.51 GiB / 40.00 MiB free]
  Total: 11 [407.43 GiB] / in use: 11 [407.43 GiB] / in no VG: 0 [0   ]

# rpm -q lvm2
lvm2-2.02.171-1.el7.x86_64

# lvchange -ay vg/raid10
  device-mapper: reload ioctl on  (253:22) failed: Invalid argument

May 16 15:06:22 virt-369 kernel: device-mapper: raid: Reshaping raid sets not yet supported. (raid layout change)
May 16 15:06:22 virt-369 kernel: device-mapper: raid: #011 0x102 vs 0x0
May 16 15:06:22 virt-369 kernel: device-mapper: raid: #011 Old layout: near w/ 2 copies
May 16 15:06:22 virt-369 kernel: ------------[ cut here ]------------
May 16 15:06:22 virt-369 kernel: WARNING: at drivers/md/dm-raid.c:508 raid10_md_layout_to_format+0x50/0x60 [dm_raid]()
May 16 15:06:22 virt-369 kernel: Modules linked in: dm_raid raid456 async_raid6_recov async_memcpy async_pq raid6_pq async_xor xor async_tx sd_mod crc_t10dif crct10dif_generic crct10dif_common sg iscsi_tcp libiscsi_tcp libiscsi scsi_trans
port_iscsi iptable_filter ppdev pcspkr i6300esb virtio_balloon i2c_piix4 i2c_core parport_pc parport nfsd auth_rpcgss nfs_acl lockd grace sunrpc dm_multipath ip_tables xfs libcrc32c ata_generic pata_acpi virtio_net virtio_blk ata_piix ser
io_raw virtio_pci virtio_ring virtio libata floppy dm_mirror dm_region_hash dm_log dm_mod
May 16 15:06:22 virt-369 kernel: CPU: 0 PID: 3211 Comm: lvchange Tainted: G        W      ------------   3.10.0-514.el7.x86_64 #1
May 16 15:06:22 virt-369 kernel: Hardware name: Red Hat KVM, BIOS 0.5.1 01/01/2011
May 16 15:06:22 virt-369 kernel: 0000000000000000 0000000040aeb462 ffff88003ce43ab8 ffffffff81685eac
May 16 15:06:22 virt-369 kernel: ffff88003ce43af0 ffffffff81085820 0000000000000000 ffff88003cae4498
May 16 15:06:22 virt-369 kernel: ffff88003cae4000 ffff880036de3000 0000000000000000 ffff88003ce43b00
May 16 15:06:22 virt-369 kernel: Call Trace:
May 16 15:06:22 virt-369 kernel: [<ffffffff81685eac>] dump_stack+0x19/0x1b
May 16 15:06:22 virt-369 kernel: [<ffffffff81085820>] warn_slowpath_common+0x70/0xb0
May 16 15:06:22 virt-369 kernel: [<ffffffff8108596a>] warn_slowpath_null+0x1a/0x20
May 16 15:06:22 virt-369 kernel: [<ffffffffa03bcc20>] raid10_md_layout_to_format+0x50/0x60 [dm_raid]
May 16 15:06:22 virt-369 kernel: [<ffffffffa03bd8fe>] super_validate.part.26+0x78e/0x7b0 [dm_raid]
May 16 15:06:22 virt-369 kernel: [<ffffffff81237edd>] ? bio_put+0x7d/0xa0
May 16 15:06:22 virt-369 kernel: [<ffffffff814fc62c>] ? sync_page_io+0x8c/0x110
May 16 15:06:22 virt-369 kernel: [<ffffffffa03bf371>] raid_ctr+0xd41/0x1680 [dm_raid]
May 16 15:06:22 virt-369 kernel: [<ffffffffa00050c1>] ? realloc_argv+0x31/0x80 [dm_mod]
May 16 15:06:22 virt-369 kernel: [<ffffffffa00056f7>] dm_table_add_target+0x177/0x460 [dm_mod]
May 16 15:06:22 virt-369 kernel: [<ffffffffa0008e37>] table_load+0x157/0x390 [dm_mod]
May 16 15:06:22 virt-369 kernel: [<ffffffffa0008ce0>] ? retrieve_status+0x1c0/0x1c0 [dm_mod]
May 16 15:06:22 virt-369 kernel: [<ffffffffa0009a35>] ctl_ioctl+0x1e5/0x500 [dm_mod]
May 16 15:06:22 virt-369 kernel: [<ffffffffa0009d63>] dm_ctl_ioctl+0x13/0x20 [dm_mod]
May 16 15:06:22 virt-369 kernel: [<ffffffff81211ed5>] do_vfs_ioctl+0x2d5/0x4b0
May 16 15:06:22 virt-369 kernel: [<ffffffff812aea5e>] ? file_has_perm+0xae/0xc0
May 16 15:06:22 virt-369 kernel: [<ffffffff81212151>] SyS_ioctl+0xa1/0xc0
May 16 15:06:22 virt-369 kernel: [<ffffffff816964c9>] system_call_fastpath+0x16/0x1b
May 16 15:06:22 virt-369 kernel: ---[ end trace 11faf4a83e1d08f1 ]---
May 16 15:06:22 virt-369 kernel: device-mapper: raid: #011 New layout: far w/ 0 copies
May 16 15:06:22 virt-369 kernel: device-mapper: table: 253:22: raid: Unable to assemble array: Invalid superblocks
May 16 15:06:22 virt-369 kernel: device-mapper: ioctl: error adding target to table

=============================================

3.10.0-514.el7.x86_64

lvm2-2.02.171-1.el7    BUILT: Wed May  3 14:05:13 CEST 2017
lvm2-libs-2.02.171-1.el7    BUILT: Wed May  3 14:05:13 CEST 2017
device-mapper-1.02.140-1.el7    BUILT: Wed May  3 14:05:13 CEST 2017
device-mapper-libs-1.02.140-1.el7    BUILT: Wed May  3 14:05:13 CEST 2017
device-mapper-event-1.02.140-1.el7    BUILT: Wed May  3 14:05:13 CEST 2017
device-mapper-event-libs-1.02.140-1.el7    BUILT: Wed May  3 14:05:13 CEST 2017
device-mapper-persistent-data-0.7.0-0.1.rc6.el7    BUILT: Mon Mar 27 17:15:46 CEST 2017
Comment 6 Heinz Mauelshagen 2017-06-06 18:34:22 UTC 
dm-raid target calls raid10_md_layout_to_format() with layout zero thus causing the WARN_ON().  Solution can be to remove it and return "unknown" for the layout
or avoid calling it in this case.
Comment 7 Heinz Mauelshagen 2017-06-06 18:35:49 UTC 
The kernel properly rejects to activate the mapping as with raid4 though but the additional WARNING is confusing.
Comment 8 Heinz Mauelshagen 2017-06-19 15:22:51 UTC 
Conclusion:
- the activation is properly rejected
- kernel creates a larger message than necessary which
  can be enhanced to avoid confusion

Moving to 7.5 to address the latter.
Comment 10 Heinz Mauelshagen 2017-06-21 15:47:57 UTC 
Closing in favour of 1463740 keeping track of the kernel message improvement.