On Thu, Mar 12, 2020 at 04:41:37PM +0000, Chris Down wrote: > The root of the hierarchy cannot have high set, so we will never reclaim > based on it. This makes that clearer and avoids another entry. > > Signed-off-by: Chris Down <chris@xxxxxxxxxxxxxx> > Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > Cc: Johannes Weiner <hannes@xxxxxxxxxxx> > Cc: Tejun Heo <tj@xxxxxxxxxx> > Cc: linux-mm@xxxxxxxxx > Cc: cgroups@xxxxxxxxxxxxxxx > Cc: linux-kernel@xxxxxxxxxxxxxxx > Cc: kernel-team@xxxxxx This makes sense, memory.high doesn't exist on the root. And the mem_cgroup_is_root() check, a simple pointer comparison, is cheaper than reading the page_counter atomic and memcg->high (which we already know to be PAGE_COUNTER_MAX). Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
