Re: [PATCH 2/5] mm: memcg: simplify objcg charge size and stock remainder math

[Vlastimil Babka (SUSE)]

On 3/2/26 20:50, Johannes Weiner wrote:
> From: Johannes Weiner <jweiner@xxxxxxxx>
> 
> Use PAGE_ALIGN() and a more natural cache remainder calculation.
> 
> Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>

Reviewed-by: Vlastimil Babka (SUSE) <vbabka@xxxxxxxxxx>

> ---
>  mm/memcontrol.c | 16 ++++++----------
>  1 file changed, 6 insertions(+), 10 deletions(-)
> 
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index a975ab3aee10..0d0a77fedb00 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -3417,7 +3417,7 @@ static void refill_obj_stock(struct obj_cgroup *objcg, unsigned int nr_bytes,
>  static int obj_cgroup_charge_account(struct obj_cgroup *objcg, gfp_t gfp, size_t size,
>  				     struct pglist_data *pgdat, enum node_stat_item idx)
>  {
> -	unsigned int nr_pages, nr_bytes;
> +	size_t charge_size, remainder;
>  	int ret;
>  
>  	if (likely(consume_obj_stock(objcg, size, pgdat, idx)))
> @@ -3446,16 +3446,12 @@ static int obj_cgroup_charge_account(struct obj_cgroup *objcg, gfp_t gfp, size_t
>  	 * bytes is (sizeof(object) + PAGE_SIZE - 2) if there is no data
>  	 * race.
>  	 */
> -	nr_pages = size >> PAGE_SHIFT;
> -	nr_bytes = size & (PAGE_SIZE - 1);
> +	charge_size = PAGE_ALIGN(size);
> +	remainder = charge_size - size;
>  
> -	if (nr_bytes)
> -		nr_pages += 1;
> -
> -	ret = obj_cgroup_charge_pages(objcg, gfp, nr_pages);
> -	if (!ret && (nr_bytes || pgdat))
> -		refill_obj_stock(objcg, nr_bytes ? PAGE_SIZE - nr_bytes : 0,
> -					 false, size, pgdat, idx);
> +	ret = obj_cgroup_charge_pages(objcg, gfp, charge_size >> PAGE_SHIFT);
> +	if (!ret && (remainder || pgdat))
> +		refill_obj_stock(objcg, remainder, false, size, pgdat, idx);
>  
>  	return ret;
>  }