On Wed, Mar 30, 2022 at 11:47:19PM +0000, Wei Yang wrote:
> For each round-trip, we assign generation on first invocation and
> compare it on subsequent invocations.
>
> Let's move them together to make it more self-explaining. Also this
> reduce a check on prev.
>
> [hannes@xxxxxxxxxxx: better comment to explain reclaim model]
>
> Signed-off-by: Wei Yang <richard.weiyang@xxxxxxxxx>
> Acked-by: Johannes Weiner <hannes@xxxxxxxxxxx>
Reviewed-by: Roman Gushchin <roman.gushchin@xxxxxxxxx>
>
> ---
> v2: a better comment from Johannes
> ---
> mm/memcontrol.c | 10 +++++++---
> 1 file changed, 7 insertions(+), 3 deletions(-)
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 5d433b79ba47..2cd8bfdec379 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -1013,7 +1013,13 @@ struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root,
> mz = root->nodeinfo[reclaim->pgdat->node_id];
> iter = &mz->iter;
>
> - if (prev && reclaim->generation != iter->generation)
> + /*
> + * On start, join the current reclaim iteration cycle.
> + * Exit when a concurrent walker completes it.
> + */
> + if (!prev)
> + reclaim->generation = iter->generation;
> + else if (reclaim->generation != iter->generation)
> goto out_unlock;
>
> while (1) {
> @@ -1075,8 +1081,6 @@ struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root,
>
> if (!memcg)
> iter->generation++;
> - else if (!prev)
> - reclaim->generation = iter->generation;
> }
>
> out_unlock:
> --
> 2.33.1
>
>
