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

[Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>]

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-druUgvl0LCNAfugRpC6u6w@public.gmane.org>
> Signed-off-by: Chris Down <chris-6Bi1550iOqEnzZ6mRAm98g@public.gmane.org>
> Cc: Andrew Morton <akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>
> Cc: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org>
> Cc: linux-mm-Bw31MaZKKs3YtjvyW6yDsg@public.gmane.org
> Cc: cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> Cc: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org
> Cc: kernel-team-b10kYP2dOMg@public.gmane.org
> Cc: stable-u79uwXL29TY76Z2rM5mHXA@public.gmane.org # 5.4.x

Acked-by: Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>