On Fri, Apr 26, 2024 at 05:37:31PM -0700, Shakeel Butt wrote:
> To reduce memory usage by the memcg events and stats, the kernel uses
> indirection table and only allocate stats and events which are being
> used by the memcg code. To make this more robust, let's add warnings
> where unexpected stats and events indexes are used.
>
> Signed-off-by: Shakeel Butt <shakeel.butt@xxxxxxxxx>
> ---
> mm/memcontrol.c | 43 ++++++++++++++++++++++++++++++++++---------
> 1 file changed, 34 insertions(+), 9 deletions(-)
>
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index 103e0e53e20a..36145089dcf5 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -671,9 +671,11 @@ unsigned long lruvec_page_state(struct lruvec *lruvec, enum node_stat_item idx)
> return node_page_state(lruvec_pgdat(lruvec), idx);
>
> i = memcg_stats_index(idx);
> - if (i >= 0) {
> + if (likely(i >= 0)) {
> pn = container_of(lruvec, struct mem_cgroup_per_node, lruvec);
> x = READ_ONCE(pn->lruvec_stats->state[i]);
> + } else {
> + pr_warn_once("%s: stat item index: %d\n", __func__, idx);
> }
I think it's generally a CONFIG_DEBUG_VM material. Do we have some extra
concerns here?
Having pr_warn_on_once() would be nice here.
