Re: [PATCH v2 1/4] memcg: store node_id instead of pglist_data pointer

[Qi Zheng]

On 5/22/26 9:19 AM, Shakeel Butt wrote:
> The struct obj_stock_pcp stores a pointer to pglist_data for the slab
> stats cached on the cpu. On 64-bit machines, this costs 8 bytes. The
> pointer is not strictly required: NODE_DATA() can recover it from the
> node id. Replace cached_pgdat with int16_t node_id and use NUMA_NO_NODE
> as the "no stats cached" sentinel.
>
> At the moment all the archs limit MAX_NUMNODES to 1024 so int16_t is
> plenty; a BUILD_BUG_ON() makes sure we notice if that ever changes.
>
> Fixes: 01b9da291c49 ("mm: memcontrol: convert objcg to be per-memcg per-node type")
> Tested-by: kernel test robot <oliver.sang@xxxxxxxxx>
> Signed-off-by: Shakeel Butt <shakeel.butt@xxxxxxxxx>
> Acked-by: Muchun Song <muchun.song@xxxxxxxxx>
> Reviewed-by: Harry Yoo (Oracle) <harry@xxxxxxxxxx>
> ---
>
> Changes since v1:
> - Added tags in the commit message
>
>   mm/memcontrol.c | 26 +++++++++++++++++++-------
>   1 file changed, 19 insertions(+), 7 deletions(-)

Acked-by: Qi Zheng <qi.zheng@xxxxxxxxx>

Thanks!