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From:   Naresh Kamboju <naresh.kamboju@linaro.org>
Date:   Thu, 28 May 2020 21:47:00 +0530
Message-ID: <CA+G9fYvDXiZ9E9EfU6h0gsJ+xaXY77mRu9Jg+J7C=X4gJ3qvLg@mail.gmail.com>
Subject: Re: mm: mkfs.ext4 invoked oom-killer on i386 - pagecache_get_page
To:     Michal Hocko <mhocko@kernel.org>,
        Yafang Shao <laoar.shao@gmail.com>
Cc:     Chris Down <chris@chrisdown.name>,
        Anders Roxell <anders.roxell@linaro.org>,
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On Thu, 28 May 2020 at 20:33, Michal Hocko <mhocko@kernel.org> wrote:
>
> On Fri 22-05-20 02:23:09, Naresh Kamboju wrote:
> > My apology !
> > As per the test results history this problem started happening from
> > Bad : next-20200430 (still reproducible on next-20200519)
> > Good : next-20200429
> >
> > The git tree / tag used for testing is from linux next-20200430 tag and reverted
> > following three patches and oom-killer problem fixed.
> >
> > Revert "mm, memcg: avoid stale protection values when cgroup is above
> > protection"
> > Revert "mm, memcg: decouple e{low,min} state mutations from protectinn checks"
> > Revert "mm-memcg-decouple-elowmin-state-mutations-from-protection-checks-fix"
>
> The discussion has fragmented and I got lost TBH.
> In http://lkml.kernel.org/r/CA+G9fYuDWGZx50UpD+WcsDeHX9vi3hpksvBAWbMgRZadb0Pkww@mail.gmail.com
> you have said that none of the added tracing output has triggered. Does
> this still hold? Because I still have a hard time to understand how
> those three patches could have the observed effects.

On the other email thread [1] this issue is concluded.

Yafang wrote on May 22 2020,

Regarding the root cause, my guess is it makes a similar mistake that
I tried to fix in the previous patch that the direct reclaimer read a
stale protection value.  But I don't think it is worth to add another
fix. The best way is to revert this commit.


[1]  [PATCH v3 2/2] mm, memcg: Decouple e{low,min} state mutations
from protection checks
https://lore.kernel.org/linux-mm/CALOAHbArZ3NsuR3mCnx_kbSF8ktpjhUF2kaaTa7Mb7ocJajsQg@mail.gmail.com/

- Naresh

> --
> Michal Hocko
> SUSE Labs