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Date:   Thu, 19 Dec 2019 12:22:11 -0800
From:   Tejun Heo <tj@kernel.org>
To:     Johannes Weiner <hannes@cmpxchg.org>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Roman Gushchin <guro@fb.com>, Michal Hocko <mhocko@suse.com>,
        linux-mm@kvack.org, cgroups@vger.kernel.org,
        linux-kernel@vger.kernel.org, kernel-team@fb.com
Subject: Re: [PATCH v2 0/3] mm: memcontrol: recursive memory protection
Message-ID: <20191219202211.GD2914998@devbig004.ftw2.facebook.com>
References: <20191219200718.15696-1-hannes@cmpxchg.org>
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On Thu, Dec 19, 2019 at 03:07:15PM -0500, Johannes Weiner wrote:
> Changes since v1:
> - improved Changelogs based on the discussion with Roman. Thanks!
> - fix div0 when recursive & fixed protection is combined
> - fix an unused compiler warning
> 
> The current memory.low (and memory.min) semantics require protection
> to be assigned to a cgroup in an untinterrupted chain from the
> top-level cgroup all the way to the leaf.
> 
> In practice, we want to protect entire cgroup subtrees from each other
> (system management software vs. workload), but we would like the VM to
> balance memory optimally *within* each subtree, without having to make
> explicit weight allocations among individual components. The current
> semantics make that impossible.

Acked-by: Tejun Heo <tj@kernel.org>

The original behavior turned out to be a significant source of
mistakes and use cases which would require older behavior just weren't
there.

Thanks.

-- 
tejun