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Date:   Mon, 16 Mar 2020 12:21:28 -0400
From:   Johannes Weiner <hannes@cmpxchg.org>
To:     Chris Down <chris@chrisdown.name>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Tejun Heo <tj@kernel.org>, linux-mm@kvack.org,
        cgroups@vger.kernel.org, linux-kernel@vger.kernel.org,
        kernel-team@fb.com
Subject: Re: [PATCH 2/2] mm, memcg: Throttle allocators based on ancestral
 memory.high
Message-ID: <20200316162128.GF67986@cmpxchg.org>
References: <80780887060514967d414b3cd91f9a316a16ab98.1584036142.git.chris@chrisdown.name>
 <8cd132f84bd7e16cdb8fde3378cdbf05ba00d387.1584036142.git.chris@chrisdown.name>
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On Thu, Mar 12, 2020 at 06:03:04PM +0000, Chris Down wrote:
> Prior to this commit, we only directly check the affected cgroup's
> memory.high against its usage. However, it's possible that we are being
> reclaimed as a result of hitting an ancestor memory.high and should be
> penalised based on that, instead.
> 
> This patch changes memory.high overage throttling to use the largest
> overage in its ancestors when considering how many penalty jiffies to
> charge. This makes sure that we penalise poorly behaving cgroups in the
> same way regardless of at what level of the hierarchy memory.high was
> breached.
> 
> Fixes: 0e4b01df8659 ("mm, memcg: throttle allocators when failing reclaim over memory.high")
> Reported-by: Johannes Weiner <hannes@cmpxchg.org>
> Signed-off-by: Chris Down <chris@chrisdown.name>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> Cc: Tejun Heo <tj@kernel.org>
> Cc: linux-mm@kvack.org
> Cc: cgroups@vger.kernel.org
> Cc: linux-kernel@vger.kernel.org
> Cc: kernel-team@fb.com
> Cc: stable@vger.kernel.org # 5.4.x

Acked-by: Johannes Weiner <hannes@cmpxchg.org>