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From:   Shakeel Butt <shakeelb@google.com>
Date:   Tue, 2 Feb 2021 14:23:57 -0800
Message-ID: <CALvZod6fHOhGN2exBSsRS4+KMzXE=1O7ALF2Hq4ehjvVFW6+ig@mail.gmail.com>
Subject: Re: [PATCH 1/7] mm: memcontrol: fix cpuhotplug statistics flushing
To:     Johannes Weiner <hannes@cmpxchg.org>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Tejun Heo <tj@kernel.org>, Michal Hocko <mhocko@suse.com>,
        Roman Gushchin <guro@fb.com>, Linux MM <linux-mm@kvack.org>,
        Cgroups <cgroups@vger.kernel.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Kernel Team <kernel-team@fb.com>
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On Tue, Feb 2, 2021 at 12:18 PM Johannes Weiner <hannes@cmpxchg.org> wrote:
>
> The memcg hotunplug callback erroneously flushes counts on the local
> CPU, not the counts of the CPU going away; those counts will be lost.
>
> Flush the CPU that is actually going away.
>
> Also simplify the code a bit by using mod_memcg_state() and
> count_memcg_events() instead of open-coding the upward flush - this is
> comparable to how vmstat.c handles hotunplug flushing.
>
> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>

I think we need Fixes: a983b5ebee572 ("mm: memcontrol: fix excessive
complexity in memory.stat reporting")

Reviewed-by: Shakeel Butt <shakeelb@google.com>