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Date:   Mon, 8 Feb 2021 13:57:07 -0500
From:   Sasha Levin <sashal@kernel.org>
To:     Avi Kivity <avi@scylladb.com>
Cc:     Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        linux-kernel@vger.kernel.org, akpm@linux-foundation.org,
        torvalds@linux-foundation.org, stable@vger.kernel.org, lwn@lwn.net,
        jslaby@suse.cz
Subject: Re: Linux 4.9.256
Message-ID: <20210208185707.GC4035784@sasha-vm>
References: <1612535085125226@kroah.com>
 <23a28990-c465-f813-52a4-f7f3db007f9d@scylladb.com>
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On Mon, Feb 08, 2021 at 05:50:21PM +0200, Avi Kivity wrote:
>On 05/02/2021 16.26, Greg Kroah-Hartman wrote:
>>I'm announcing the release of the 4.9.256 kernel.
>>
>>This, and the 4.4.256 release are a little bit "different" than normal.
>>
>>This contains only 1 patch, just the version bump from .255 to .256 which ends
>>up causing the userspace-visable LINUX_VERSION_CODE to behave a bit differently
>>than normal due to the "overflow".
>>
>>With this release, KERNEL_VERSION(4, 9, 256) is the same as KERNEL_VERSION(4, 10, 0).
>
>
>I think this is a bad idea. Many kernel features can only be 
>discovered by checking the kernel version. If a feature was introduced 
>in 4.10, then an application can be tricked into thinking a 4.9 kernel 
>has it.
>
>
>IMO, better to stop LINUX_VERSION_CODE at 255 and introduce a 

In the upstream (and new -stable fix) we did this part.

>LINUX_VERSION_CODE_IMPROVED that has more bits for patchlevel.

Do you have a usecase where it's actually needed? i.e. userspace that
checks for -stable patchlevels?

-- 
Thanks,
Sasha