Hello. On Mon, Apr 07, 2025 at 12:23:15PM -0400, Waiman Long <long...@redhat.com> wrote: > --- a/mm/memcontrol-v1.h > +++ b/mm/memcontrol-v1.h > @@ -22,8 +22,6 @@ > iter != NULL; \ > iter = mem_cgroup_iter(NULL, iter, NULL)) > > -unsigned long mem_cgroup_usage(struct mem_cgroup *memcg, bool swap); > -
Hm, maybe keep it for v1 only where mem_cgroup_usage has meaning for
memsw (i.e. do the opposite and move the function definition to -v1.c).
> void drain_all_stock(struct mem_cgroup *root_memcg);
>
> unsigned long memcg_events(struct mem_cgroup *memcg, int event);
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index b620d74b0f66..a771a0145a12 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -5963,6 +5963,10 @@ static void shrink_node_memcgs(pg_data_t *pgdat,
> struct scan_control *sc)
>
> mem_cgroup_calculate_protection(target_memcg, memcg);
>
> + /* Skip memcg with no usage */
> + if (!mem_cgroup_usage(memcg, false))
> + continue;
> +
(Not only for v2), there is mem_cgroup_size() for this purpose (already
used in mm/vmscan.c).
> if (mem_cgroup_below_min(target_memcg, memcg)) {
> /*
> * Hard protection.
> diff --git a/tools/testing/selftests/cgroup/test_memcontrol.c
> b/tools/testing/selftests/cgroup/test_memcontrol.c
> index 16f5d74ae762..bab826b6b7b0 100644
> --- a/tools/testing/selftests/cgroup/test_memcontrol.c
> +++ b/tools/testing/selftests/cgroup/test_memcontrol.c
> @@ -525,8 +525,13 @@ static int test_memcg_protection(const char *root, bool
> min)
> goto cleanup;
> }
>
> + /*
> + * Child 2 has memory.low=0, but some low protection is still being
> + * distributed down from its parent with memory.low=50M. So the low
> + * event count will be non-zero.
> + */
> for (i = 0; i < ARRAY_SIZE(children); i++) {
> - int no_low_events_index = 1;
> + int no_low_events_index = 2;
See suggestion in
https://lore.kernel.org/lkml/awgbdn6gwnj4kfaezsorvopgsdyoty3yahdeanqvoxstz2w2ke@xc3sv43elkz5/
HTH,
Michal
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