linux-kernel - Re: [PATCH 4.20 71/92] Revert "mm: slowly shrink slabs with a relatively small number of objects"

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Message-ID: <20190218193452.GV10616@sasha-vm>
Date:   Mon, 18 Feb 2019 14:34:52 -0500
From:   Sasha Levin <sashal@...nel.org>
To:     Rik van Riel <riel@...riel.com>
Cc:     Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        linux-kernel@...r.kernel.org, stable@...r.kernel.org,
        Dave Chinner <dchinner@...hat.com>,
        Wolfgang Walter <linux@...m.de>, Roman Gushchin <guro@...com>,
        Spock <dairinin@...il.com>, Michal Hocko <mhocko@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: Re: [PATCH 4.20 71/92] Revert "mm: slowly shrink slabs with a
 relatively small number of objects"

On Mon, Feb 18, 2019 at 10:30:44AM -0500, Rik van Riel wrote:
>On Mon, 2019-02-18 at 14:43 +0100, Greg Kroah-Hartman wrote:
>> 4.20-stable review patch.  If anyone has any objections, please let
>> me know.
>>
>> ------------------
>>
>> From: Dave Chinner <dchinner@...hat.com>
>>
>> commit a9a238e83fbb0df31c3b9b67003f8f9d1d1b6c96 upstream.
>>
>> This reverts commit 172b06c32b9497 ("mm: slowly shrink slabs with a
>> relatively small number of objects").
>
>This revert will result in the slab caches of dead
>cgroups with a small number of remaining objects never
>getting reclaimed, which can be a memory leak in some
>configurations.

What's the "right" choice though? we get either leaky cgroups or hanging
xfs.

>But hey, that's your tradeoff to make.

I don't think that any decision was made here, the stable tree simply
follows upstream with regards to fixes and bugs such as these: we remain
"bug compatible" with upstream in these scenarios, there was no decision
made to prefer either bug.

--
Thanks,
Sasha