Re: [PATCH 2/2] mm, memcg: Throttle allocators based on ancestral memory.high

[Johannes Weiner]

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@xxxxxxxxxxx>
> Signed-off-by: Chris Down <chris@xxxxxxxxxxxxxx>
> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
> Cc: Tejun Heo <tj@xxxxxxxxxx>
> Cc: linux-mm@xxxxxxxxx
> Cc: cgroups@xxxxxxxxxxxxxxx
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Cc: kernel-team@xxxxxx
> Cc: stable@xxxxxxxxxxxxxxx # 5.4.x

Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>