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Date:   Thu, 21 May 2020 11:55:15 +0200
From:   Michal Hocko <mhocko@kernel.org>
To:     Naresh Kamboju <naresh.kamboju@linaro.org>,
        Chris Down <chris@chrisdown.name>
Cc:     Yafang Shao <laoar.shao@gmail.com>,
        Anders Roxell <anders.roxell@linaro.org>,
        "Linux F2FS DEV, Mailing List" 
        <linux-f2fs-devel@lists.sourceforge.net>,
        linux-ext4 <linux-ext4@vger.kernel.org>,
        linux-block <linux-block@vger.kernel.org>,
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        open list <linux-kernel@vger.kernel.org>,
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        Jaegeuk Kim <jaegeuk@kernel.org>,
        Theodore Ts'o <tytso@mit.edu>, Chao Yu <chao@kernel.org>,
        Hugh Dickins <hughd@google.com>,
        Andrea Arcangeli <aarcange@redhat.com>,
        Matthew Wilcox <willy@infradead.org>,
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Subject: Re: mm: mkfs.ext4 invoked oom-killer on i386 - pagecache_get_page
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On Wed 20-05-20 20:09:06, Chris Down wrote:
> Hi Naresh,
> 
> Naresh Kamboju writes:
> > As a part of investigation on this issue LKFT teammate Anders Roxell
> > git bisected the problem and found bad commit(s) which caused this problem.
> > 
> > The following two patches have been reverted on next-20200519 and retested the
> > reproducible steps and confirmed the test case mkfs -t ext4 got PASS.
> > ( invoked oom-killer is gone now)
> > 
> > Revert "mm, memcg: avoid stale protection values when cgroup is above
> > protection"
> >    This reverts commit 23a53e1c02006120f89383270d46cbd040a70bc6.
> > 
> > Revert "mm, memcg: decouple e{low,min} state mutations from protection
> > checks"
> >    This reverts commit 7b88906ab7399b58bb088c28befe50bcce076d82.
> 
> Thanks Anders and Naresh for tracking this down and reverting.
> 
> I'll take a look tomorrow. I don't see anything immediately obviously wrong
> in either of those commits from a (very) cursory glance, but they should
> only be taking effect if protections are set.

Agreed. If memory.{low,min} is not used then the patch should be
effectively a nop. Btw. do you see the problem when booting with
cgroup_disable=memory kernel command line parameter?

I suspect that something might be initialized for memcg incorrectly and
the patch just makes it more visible for some reason.
-- 
Michal Hocko
SUSE Labs