Re: [PATCH 1/2] mm: Report success more often from filemap_map_folio_range()

[Yin Fengwei <fengwei.yin@intel.com>]

On 9/20/23 11:53, Matthew Wilcox (Oracle) wrote:
> Even though we had successfully mapped the relevant page, we would
> rarely return success from filemap_map_folio_range().  That leads to
> falling back from the VMA lock path to the mmap_lock path, which is a
> speed & scalability issue.  Found by inspection.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> Fixes: 617c28ecab22 ("filemap: batch PTE mappings")
> ---
Reviewed-by: Yin Fengwei <fengwei.yin@intel.com>

Thanks a lot for taking care of this.

Regards
Yin, Fengwei



>  mm/filemap.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/filemap.c b/mm/filemap.c
> index 582f5317ff71..580d0b2b1a7c 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -3506,7 +3506,7 @@ static vm_fault_t filemap_map_folio_range(struct vm_fault *vmf,
>  		if (count) {
>  			set_pte_range(vmf, folio, page, count, addr);
>  			folio_ref_add(folio, count);
> -			if (in_range(vmf->address, addr, count))
> +			if (in_range(vmf->address, addr, count * PAGE_SIZE))
>  				ret = VM_FAULT_NOPAGE;
>  		}
>  
> @@ -3520,7 +3520,7 @@ static vm_fault_t filemap_map_folio_range(struct vm_fault *vmf,
>  	if (count) {
>  		set_pte_range(vmf, folio, page, count, addr);
>  		folio_ref_add(folio, count);
> -		if (in_range(vmf->address, addr, count))
> +		if (in_range(vmf->address, addr, count * PAGE_SIZE))
>  			ret = VM_FAULT_NOPAGE;
>  	}
>