mm/memcg: move generation assignment and comparison together

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@cmpxchg.org: better comment to explain reclaim model]
Link: https://lkml.kernel.org/r/20220330234719.18340-4-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Wei Yang 2022-04-28 23:15:59 -07:00 committed by akpm
parent 89d8330ccf
commit a9320aae68

View file

@ -1021,7 +1021,13 @@ 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) {
@ -1083,8 +1089,6 @@ struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root,
if (!memcg)
iter->generation++;
else if (!prev)
reclaim->generation = iter->generation;
}
out_unlock: