Re: [PATCH v2 19/46] mm/migrate: Add folio_migrate_flags()

[Christoph Hellwig]

>  	/*
>  	 * Please do not reorder this without considering how mm/ksm.c's
>  	 * get_ksm_page() depends upon ksm_migrate_page() and PageSwapCache().
>  	 */
> -	if (PageSwapCache(page))
> -		ClearPageSwapCache(page);
> -	ClearPagePrivate(page);
> -	set_page_private(page, 0);
> +	if (folio_swapcache(folio))
> +		folio_clear_swapcache_flag(folio);
> +	folio_clear_private_flag(folio);
> +
> +	/* page->private contains hugetlb specific flags */
> +	if (!folio_hugetlb(folio))
> +		folio->private = NULL;

Ymmm. Dosn't the ->private handling change now?  Given that you
added a comment it seems intentional, but I do not understand why
it changes as part of the conversion.