2020-12-15 14:15:30

by Johannes Weiner

[permalink] [raw]
Subject: Re: [v2 PATCH 2/9] mm: memcontrol: use shrinker_rwsem to protect shrinker_maps allocation

On Mon, Dec 14, 2020 at 02:37:15PM -0800, Yang Shi wrote:
> Since memcg_shrinker_map_size just can be changd under holding shrinker_rwsem
> exclusively, the read side can be protected by holding read lock, so it sounds
> superfluous to have a dedicated mutex. This should not exacerbate the contention
> to shrinker_rwsem since just one read side critical section is added.
>
> Signed-off-by: Yang Shi <[email protected]>

Acked-by: Johannes Weiner <[email protected]>

Thanks Yang, this is a step in the right direction. It would still be
nice to also drop memcg_shrinker_map_size and (trivially) derive that
value from shrinker_nr_max where necessary. It is duplicate state.