Re: Issues with md raid 1 on kernel 6.18 after booting kernel 6.19rc1 once

[Bugreports61 <bugreports61@gmail.com>]

Hi,


reading the threads it was now decided that only newly created arrays 
will get the lbs adjustment and patches to make it work on older kernels 
will not happen:


How do i get back my md raid1 to a state which makes it usable again on 
older kernels ?

Is it  safe to simply mdadm --create --assume-clean /dev/mdX /sdX /sdY 
on kernel 6.18 to get the old superblock 1.2 information back without 
loosing data ?


My thx !


Am 17.12.25 um 14:24 schrieb Li Nan:
>
>
> 在 2025/12/17 15:06, Yu Kuai 写道:
>> Hi,
>>
>> 在 2025/12/17 14:58, BugReports 写道:
>>> Hi,
>>>
>>> i hope i am reaching out to the correct mailing list and this is the
>>> way to correctly report issues with rc kernels.
>>>
>>> I installed kernel 6.19-rc 1 recently (with linux-tkg, but that should
>>> not matter).  Booting the 6.19 rc1 kernel worked fine and i could
>>> access my md raid 1.
>>>
>>> After that i wanted to switch back to kernel 6.18.1 and noticed the
>>> following:
>>>
>>> - I can not access the raid 1 md anymore as it does not assemble 
>>> anymore
>>>
>>> - The following error message shows up when i try to assemble the raid:
>>>
>>> |mdadm: /dev/sdc1 is identified as a member of /dev/md/1, slot 0.
>>> mdadm: /dev/sda1 is identified as a member of /dev/md/1, slot 1.
>>> mdadm: failed to add /dev/sda1 to /dev/md/1: Invalid argument mdadm:
>>> failed to add /dev/sdc1 to /dev/md/1: Invalid argument - The following
>>> error shows up in dmesg: ||[Di, 16. Dez 2025, 11:50:38] md: md1
>>> stopped. [Di, 16. Dez 2025, 11:50:38] md: sda1 does not have a valid
>>> v1.2 superblock, not importing! [Di, 16. Dez 2025, 11:50:38] md:
>>> md_import_device returned -22 [Di, 16. Dez 2025, 11:50:38] md: sdc1
>>> does not have a valid v1.2 superblock, not importing! [Di, 16. Dez
>>> 2025, 11:50:38] md: md_import_device returned -22 [Di, 16. Dez 2025,
>>> 11:50:38] md: md1 stopped. - mdadm --examine used with kerne 6.18
>>> shows the following : ||cat mdadmin618.txt /dev/sdc1: Magic : a92b4efc
>>> Version : 1.2 Feature Map : 0x1 Array UUID :
>>> 3b786bf1:559584b0:b9eabbe2:82bdea18 Name : gamebox:1 (local to host
>>> gamebox) Creation Time : Tue Nov 26 20:39:09 2024 Raid Level : raid1
>>> Raid Devices : 2 Avail Dev Size : 3859879936 sectors (1840.53 GiB
>>> 1976.26 GB) Array Size : 1929939968 KiB (1840.53 GiB 1976.26 GB) Data
>>> Offset : 264192 sectors Super Offset : 8 sectors Unused Space :
>>> before=264112 sectors, after=0 sectors State : clean Device UUID :
>>> 9f185862:a11d8deb:db6d708e:a7cc6a91 Internal Bitmap : 8 sectors from
>>> superblock Update Time : Mon Dec 15 22:40:46 2025 Bad Block Log : 512
>>> entries available at offset 16 sectors Checksum : f11e2fa5 - correct
>>> Events : 2618 Device Role : Active device 0 Array State : AA ('A' ==
>>> active, '.' == missing, 'R' == replacing) /dev/sda1: Magic : a92b4efc
>>> Version : 1.2 Feature Map : 0x1 Array UUID :
>>> 3b786bf1:559584b0:b9eabbe2:82bdea18 Name : gamebox:1 (local to host
>>> gamebox) Creation Time : Tue Nov 26 20:39:09 2024 Raid Level : raid1
>>> Raid Devices : 2 Avail Dev Size : 3859879936 sectors (1840.53 GiB
>>> 1976.26 GB) Array Size : 1929939968 KiB (1840.53 GiB 1976.26 GB) Data
>>> Offset : 264192 sectors Super Offset : 8 sectors Unused Space :
>>> before=264112 sectors, after=0 sectors State : clean Device UUID :
>>> fc196769:0e25b5af:dfc6cab6:639ac8f9 Internal Bitmap : 8 sectors from
>>> superblock Update Time : Mon Dec 15 22:40:46 2025 Bad Block Log : 512
>>> entries available at offset 16 sectors Checksum : 4d0d5f31 - correct
>>> Events : 2618 Device Role : Active device 1 Array State : AA ('A' ==
>>> active, '.' == missing, 'R' == replacing)|
>>> |- Mdadm --detail shows the following in 6.19 rc1 (i am using 6.19
>>> output as it does not work anymore in 6.18.1): ||/dev/md1: Version :
>>> 1.2 Creation Time : Tue Nov 26 20:39:09 2024 Raid Level : raid1 Array
>>> Size : 1929939968 (1840.53 GiB 1976.26 GB) Used Dev Size : 1929939968
>>> (1840.53 GiB 1976.26 GB) Raid Devices : 2 Total Devices : 2
>>> Persistence : Superblock is persistent Intent Bitmap : Internal Update
>>> Time : Tue Dec 16 13:14:10 2025 State : clean Active Devices : 2
>>> Working Devices : 2 Failed Devices : 0 Spare Devices : 0 Consistency
>>> Policy : bitmap Name : gamebox:1 (local to host gamebox) UUID :
>>> 3b786bf1:559584b0:b9eabbe2:82bdea18 Events : 2618 Number Major Minor
>>> RaidDevice State 0 8 33 0 active sync /dev/sdc1 1 8 1 1 active sync
>>> /dev/sda1|
>>>
>>>
>>> I didn't spot any obvious issue in the mdadm --examine on kernel 6.18
>>> pointing to why it thinks this is not a valid 1.2 superblock.
>>>
>>> The mdraid still works nicely on kernel 6.19 but i am unable to use it
>>> on kernel 6.18 (worked fine before booting 6.19).
>>>
>>> Is kernel 6.19 rc1 doing adjustments on the md superblock when the md
>>> is used which are not compatible with older kernels (the md was
>>> created already in Nov 2024)?
>>
>> I believe this is because lbs is now stored in metadata of md arrays, 
>> while this field is still
>> not defined in old kernels, see dtails in the following set:
>>
>> [PATCH v9 0/5] make logical block size configurable - linan666 
>> <https://lore.kernel.org/linux-raid/20251103125757.1405796-1-linan666@huaweicloud.com/>
>>
>> We'll have to backport following patch into old kernels to make new 
>> arrays to assemble in old
>> kernels.
>>
>> https://lore.kernel.org/linux-raid/20251103125757.1405796-5-linan666@huaweicloud.com 
>>
>>
>> +CC Nan, would you mind backport above patch into stable kernels?
>>
>
> Sent to stable from 6.18 to 5.10
>
> https://lore.kernel.org/stable/20251217130513.2706844-1-linan666@huaweicloud.com/T/#u 
>
> https://lore.kernel.org/stable/20251217130935.2712267-1-linan666@huaweicloud.com/T/#u 
>
>