linux-kernel - Re: Known and unfixed active data loss bug in MM + XFS with large folios since Dec 2021 (any kernel from 6.1 upwards)

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Message-ID: <0bdce668-5711-4315-ab05-1a3492cb8bf6@kernel.dk>
Date: Fri, 27 Sep 2024 08:58:24 -0600
From: Jens Axboe <axboe@...nel.dk>
To: Sam James <sam@...too.org>, Kairui Song <ryncsn@...il.com>,
 Greg KH <gregkh@...uxfoundation.org>
Cc: stable@...nel.org, clm@...a.com, Matthew Wilcox <willy@...radead.org>,
 ct@...ingcircus.io, david@...morbit.com, dqminh@...udflare.com,
 linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-mm@...ck.org, linux-xfs@...r.kernel.org, regressions@...mhuis.info,
 regressions@...ts.linux.dev, torvalds@...ux-foundation.org
Subject: Re: Known and unfixed active data loss bug in MM + XFS with large
 folios since Dec 2021 (any kernel from 6.1 upwards)

On 9/27/24 8:51 AM, Sam James wrote:
> Kairui Song <ryncsn@...il.com> writes:
> 
>> On Wed, Sep 25, 2024 at 1:16?AM Sam James <sam@...too.org> wrote:
>>>
>>> Kairui, could you send them to the stable ML to be queued if Willy is
>>> fine with it?
>>>
>>
>> Hi Sam,
> 
> Hi Kairui,
> 
>>
>> Thanks for adding me to the discussion.
>>
>> Yes I'd like to, just not sure if people are still testing and
>> checking the commits.
>>
>> And I haven't sent seperate fix just for stable fix before, so can
>> anyone teach me, should I send only two patches for a minimal change,
>> or send a whole series (with some minor clean up patch as dependency)
>> for minimal conflicts? Or the stable team can just pick these up?
> 
> Please see https://www.kernel.org/doc/html/v6.11/process/stable-kernel-rules.html.
> 
> If Option 2 can't work (because of conflicts), please follow Option 3
> (https://www.kernel.org/doc/html/v6.11/process/stable-kernel-rules.html#option-3).
> 
> Just explain the background and link to this thread in a cover letter
> and mention it's your first time. Greg didn't bite me when I fumbled my
> way around it :)
> 
> (greg, please correct me if I'm talking rubbish)

It needs two cherry picks, one of them won't pick cleanly. So I suggest
whoever submits this to stable does:

1) Cherry pick the two commits, fixup the simple issue with one of them.
   I forget what it was since it's been a week and a half since I did
   it, but it's trivial to fixup.

   Don't forget to add the "commit XXX upstream" to the commit message.

2) Test that it compiles and boots and send an email to
   stable@...r.kernel.org with the patches attached and CC the folks in
   this thread, to help spot if there are mistakes.

and that should be it. Worst case, we'll need a few different patches
since this affects anything back to 5.19, and each currently maintained
stable kernel version will need it.

-- 
Jens Axboe