Re: [regression] Bug 216932 - io_uring with libvirt cause kernel NULL pointer dereference since 6.1.5

[Jens Axboe]

On 1/16/23 8:44 AM, Jens Axboe wrote:
> On 1/16/23 7:49 AM, Greg Kroah-Hartman wrote:
>> On Mon, Jan 16, 2023 at 07:13:40AM -0700, Jens Axboe wrote:
>>> On 1/16/23 6:42 AM, Jens Axboe wrote:
>>>> On 1/16/23 6:17?AM, Linux kernel regression tracking (Thorsten Leemhuis) wrote:
>>>>> Hi, this is your Linux kernel regression tracker.
>>>>>
>>>>> I noticed a regression report in bugzilla.kernel.org. As many (most?)
>>>>> kernel developer don't keep an eye on it, I decided to forward it by
>>>>> mail. Quoting from https://bugzilla.kernel.org/show_bug.cgi?id=216932 :
>>>>
>>>> Looks like:
>>>>
>>>> commit 6d47e0f6a535701134d950db65eb8fe1edf0b575
>>>> Author: Jens Axboe <axboe@xxxxxxxxx>
>>>> Date:   Wed Jan 4 08:52:06 2023 -0700
>>>>
>>>>     block: don't allow splitting of a REQ_NOWAIT bio
>>>>
>>>> got picked up by stable, but not the required prep patch:
>>>>
>>>>
>>>> commit 613b14884b8595e20b9fac4126bf627313827fbe
>>>> Author: Jens Axboe <axboe@xxxxxxxxx>
>>>> Date:   Wed Jan 4 08:51:19 2023 -0700
>>>>
>>>>     block: handle bio_split_to_limits() NULL return
>>>>
>>>> Greg/team, can you pick the latter too? It'll pick cleanly for
>>>> 6.1-stable, not sure how far back the other patch has gone yet.
>>>
>>> Looked back, and 5.15 has it too, but the cherry-pick won't work
>>> on that kernel.
>>>
>>> Here's one for 5.15-stable that I verified crashes before this one,
>>> and works with it. Haven't done an allmodconfig yet...
>>
>> All now queued up, thanks!
> 
> Thanks Greg! This one was my fault, as it was a set of 2 patches and
> I only marked 2/2 for stable. But how is that best handled? 1/2 could've
> been marked stable as well, but I don't think that would have prevented
> 2/2 applying fine and 1/2 failing and hence not getting queued up until
> I would've done a backport.
> 
> What's the recommended way to describe the dependency that you only
> want 2/2 applied when 1/2 is in as well?

What I'm asking is if we have something like Depends-on or similar
that would explain this dependency. Then patch 2/2 could have:

Depends-on: 613b14884b85 ("block: handle bio_split_to_limits() NULL return")

and then it'd be clear that either both get added, or none of them.

-- 
Jens Axboe