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

Am 17.12.25 um 08:41 schrieb Yu Kuai:
>>>> We'll have to backport following patch into old kernels to make
>>>> new arrays to assemble in old kernels. ....
>>>>
>>>> The md array which i am talking about was not created with kernel
>>>> 6.19, it was created sometime in 2024.
>>>>
>>>> It was just used in kernel 6.19 and that broke compatibility with
>>>> my 6.18 kernel.
>>>
>>> I know, I mean any array that is created or assembled in new kernels
>>> will now have lsb field stored in metadata. This field is not
>>> defined in old kernels and that's why array can't assembled in old
>>> kernels, due to unknown metadata.
>>>
>>> This is what we have to do for new features, and we're planning to
>>> avoid the forward compatibility issue with the above patch that I
>>> mentioned.
>> Is there really no way around it? Just testing a new kernel and being
>> able to go back must be supported in my opinion, at least between one
>> or two LTS versions.
> 
> As I said, following patch should be backported to LTS kernels to avoid the problem.
> https://lore.kernel.org/linux-raid/[email protected]

that's nothing you can rely on - yo can write as many pachtes as you 
will but if and when they are included in random binary kernels is not 
controllable

the current situation is somebody tests a new kernel and after that his 
RAID got unrevertable changed and can't be used with the previous kernel

that's not expectable nor acceptable