Re: [PATCH v2 1/2] mm/filemap: count only the faulting address as a mmap hit

[Matthew Wilcox]

On Mon, Apr 27, 2026 at 04:57:50PM +0000, fujunjie wrote:
> -		/*
> -		 * If there are too many folios that are recently evicted
> -		 * in a file, they will probably continue to be evicted.
> -		 * In such situation, read-ahead is only a waste of IO.
> -		 * Don't decrease mmap_miss in this scenario to make sure
> -		 * we can stop read-ahead.
> -		 */

I'm sad to lose this comment.  Why not move it to ...

> +		ret |= map_ret;

here?

> +		if ((map_ret & VM_FAULT_NOPAGE) &&
> +		    !folio_test_workingset(folio)) {
> +			unsigned short mmap_miss;
> +
> +			mmap_miss = READ_ONCE(file->f_ra.mmap_miss);
> +			if (mmap_miss)
> +				WRITE_ONCE(file->f_ra.mmap_miss,
> +					   mmap_miss - 1);
> +		}