Re: [PATCH -next v2 09/19] mm: mprotect: use a folio in change_pte_range()

[Matthew Wilcox]

On Fri, Oct 13, 2023 at 04:55:53PM +0800, Kefeng Wang wrote:
> Use a folio in change_pte_range() to save three compound_head() calls.

Yes, but here we have a change of behaviour, which should be argued
is desirable.  Before if a partial THP was mapped, or a fs large
folio, we would do this to individual pages.  Now we're doing it to the
entire folio.  Is that desirable?  I don't have the background to argue
either way.

> @@ -157,7 +159,7 @@ static long change_pte_range(struct mmu_gather *tlb,
>  					continue;
>  				if (sysctl_numa_balancing_mode & NUMA_BALANCING_MEMORY_TIERING &&
>  				    !toptier)
> -					xchg_page_access_time(page,
> +					folio_xchg_access_time(folio,
>  						jiffies_to_msecs(jiffies));
>  			}