Re: [PATCH 3/3] mm/mglru: retry the same type once if isolation fails due to races

On 8/20/2026 12:56 PM, Barry Song (Xiaomi) wrote:
> If we are not exhausted (i.e., there are still folios in the
> reclaimable generations) but fail to isolate any folios due to
> promotions, protections, or races, retry once more to avoid going
> through the outer loop again.
> 
> Signed-off-by: Barry Song (Xiaomi) <[email protected]>
> ---
>   mm/vmscan.c | 10 +++++++++-
>   1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 1f2e574b0061..1f302386d8ab 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -4862,7 +4862,7 @@ static int isolate_folios(unsigned long nr_to_scan, struct lruvec *lruvec,
>   	bool type_fallback_allowed = !is_single_type_reclaim(swappiness);
>   	int type = get_type_to_scan(lruvec, swappiness);
>   	int total_scanned = 0, scanned, tier;
> -	bool exhausted;
> +	bool exhausted, tried = false;
>   
>   retry:
>   	tier = get_tier_idx(lruvec, type);
> @@ -4885,6 +4885,14 @@ static int isolate_folios(unsigned long nr_to_scan, struct lruvec *lruvec,
>   		type_fallback_allowed = false;
>   		goto retry;
>   	}
> +	/*
> +	 * We are not exhausted, but failed to isolate any folios due to
> +	 * promotions, protections, or races. Retry once to avoid a larger loop.
> +	 */
> +	if (!exhausted && !tried) {
> +		tried = true;
> +		goto retry;
> +	}
>   
>   	return total_scanned;
>   }

LGTM.

Reviewed-by: Ridong Chen <[email protected]>

-- 
Best regards
Ridong