Re: [linus:master] [readahead] ab4443fe3c: vm-scalability.throughput -21.4% regression

[Yin, Fengwei]

Hi Matthew,

On 3/8/2024 2:19 AM, Matthew Wilcox wrote:
>   		/* Align with smaller pages if needed */
>   		if (index & ((1UL << order) - 1))
>   			order = __ffs(index);
> +		/* Avoid wrap */
> +		if (index + (1UL << order) == 0)
> +			order--;
>   		/* Don't allocate pages past EOF */
> -		while (index + (1UL << order) - 1 > limit)
> +		while (index + (1UL << order) - 1 > last)
The lockup is related with this line. When index == (last + 1),
deadloop here.


Regards
Yin, Fengwei

>   			order--;