Re: [RFC PATCH v3 bpf-next 3/5] sched: add helpers for numa balancing

[bot+bpf-ci]

> sched: add helpers for numa balancing

TL;DR: Nits only: redundant parentheses around the new numab_in_tiering_mode()
helper calls in should_numa_migrate_memory() and migrate_misplaced_folio()
could be dropped.

> diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> index 71dc47d6114d..066818498c76 100644
> --- a/kernel/sched/fair.c
> +++ b/kernel/sched/fair.c

[ ... ]

> @@ -2963,8 +2965,8 @@ bool should_numa_migrate_memory(struct task_struct *p, struct folio *folio,
>  	this_cpupid = cpu_pid_to_cpupid(dst_cpu, current->pid);
>  	last_cpupid = folio_xchg_last_cpupid(folio, this_cpupid);
>  
> -	if (!(sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING) &&
> -	    !node_is_toptier(src_nid) && !cpupid_valid(last_cpupid))
> +	if (!(numab_in_tiering_mode()) && !node_is_toptier(src_nid) &&
> +	    !cpupid_valid(last_cpupid))
>  		return false;

this isn't a bug, but could the extra parentheses in
!(numab_in_tiering_mode()) be dropped here?  They were needed around the
old bitwise test, and the other converted sites such as
task_numa_fault() call the helper without them.

[ ... ]

> diff --git a/mm/migrate.c b/mm/migrate.c
> index 15b45832bcfa..a622df9a9b42 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c

[ ... ]

> @@ -2770,7 +2771,7 @@ int migrate_misplaced_folio(struct folio *folio, int node)
>  	if (nr_succeeded) {
>  		count_vm_numa_events(NUMA_PAGE_MIGRATE, nr_succeeded);
>  		count_memcg_events(memcg, NUMA_PAGE_MIGRATE, nr_succeeded);
> -		if ((sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING)
> +		if ((numab_in_tiering_mode())
>  		    && !node_is_toptier(folio_nid(folio))
>  		    && node_is_toptier(node))
>  			mod_lruvec_state(lruvec, PGPROMOTE_SUCCESS, nr_succeeded);

The same applies to the parentheses in
if ((numab_in_tiering_mode()) here.


---
AI reviewed your patch. Please fix the bug or email reply why it's not a bug.
See: https://github.com/kernel-patches/vmtest/blob/master/ci/claude/README.md

CI run summary: https://github.com/kernel-patches/bpf/actions/runs/39213018427