linux-ext4 - Re: [PATCH] ext4: Fix deadlock due to mbcache entry corruption

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Message-ID: <Y5LbTkjORxVhgpKy@sashalap>
Date:   Fri, 9 Dec 2022 01:53:02 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     Thorsten Leemhuis <regressions@...mhuis.info>
Cc:     Theodore Ts'o <tytso@....edu>, Jan Kara <jack@...e.cz>,
        Andreas Dilger <adilger.kernel@...ger.ca>,
        linux-ext4@...r.kernel.org, stable@...r.kernel.org,
        Thilo Fromm <t-lo@...ux.microsoft.com>,
        Jeremi Piotrowski <jpiotrowski@...ux.microsoft.com>,
        Andreas Gruenbacher <agruenba@...hat.com>
Subject: Re: [PATCH] ext4: Fix deadlock due to mbcache entry corruption

On Fri, Dec 09, 2022 at 07:31:03AM +0100, Thorsten Leemhuis wrote:
>On 09.12.22 07:12, Theodore Ts'o wrote:
>> On Thu, Dec 08, 2022 at 06:16:02PM +0100, Thorsten Leemhuis wrote:
>>>
>>> Maybe I should talk to Greg again to revert backported changes like
>>> 1be97463696c until fixes for them are ready.
>>
>> The fix is in the ext4 git tree, and it's ready to be pushed to Linus
>> when the merge window opens --- presumably, on Sunday.
>
>Thx!
>
>> So it's probably not worth it to revert the backported change, only to
>> reapply immediately afterwards.
>
>Definitely agreed, I was more taking in the general sense (sorry, should
>have been clearer), as it's not the first time some backport exposes
>existing problems that take a while to get analyzed and fixed in
>mainline. Which is just how it is sometimes, hence a revert and a
>reapply of that backport (once the fix is available) in stable/longterm
>sounds appropriate to me to prevent users from running into known problems.

It's a balancing act: reverting a fix would mean that we reintroduce an
issue that was previously fixed back to users. It's not always the right
thing to do, and sometimes we won't.

-- 
Thanks,
Sasha