linux-kernel - Re: [PATCH v3 13/16] mm: remove non_swap_entry() and use softleaf helpers instead

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Message-ID: <73d414c1-8cdf-4d61-baa0-e4d689b3973b@suse.cz>
Date: Thu, 27 Nov 2025 18:12:31 +0100
From: Vlastimil Babka <vbabka@...e.cz>
To: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
 Andrew Morton <akpm@...ux-foundation.org>
Cc: Christian Borntraeger <borntraeger@...ux.ibm.com>,
 Janosch Frank <frankja@...ux.ibm.com>,
 Claudio Imbrenda <imbrenda@...ux.ibm.com>,
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 Gerald Schaefer <gerald.schaefer@...ux.ibm.com>,
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 Arnd Bergmann <arnd@...db.de>, Zi Yan <ziy@...dia.com>,
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Subject: Re: [PATCH v3 13/16] mm: remove non_swap_entry() and use softleaf
 helpers instead

On 11/10/25 23:21, Lorenzo Stoakes wrote:
> There is simply no need for the hugely confusing concept of 'non-swap' swap
> entries now we have the concept of softleaf entries and relevant
> softleaf_xxx() helpers.
> 
> Adjust all callers to use these instead and remove non_swap_entry()
> altogether.
> 
> No functional change intended.
> 
> Signed-off-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>

Nice!

Reviewed-by: Vlastimil Babka <vbabka@...e.cz>

> @@ -1430,19 +1429,20 @@ static long move_pages_ptes(struct mm_struct *mm, pmd_t *dst_pmd, pmd_t *src_pmd
>  					orig_dst_pte, orig_src_pte, dst_pmd,
>  					dst_pmdval, dst_ptl, src_ptl, &src_folio,
>  					len);
> -	} else {
> +	} else { /* !pte_present() */
>  		struct folio *folio = NULL;
> +		const softleaf_t entry = softleaf_from_pte(orig_src_pte);
>  
> -		entry = pte_to_swp_entry(orig_src_pte);
> -		if (non_swap_entry(entry)) {
> -			if (is_migration_entry(entry)) {
> -				pte_unmap(src_pte);
> -				pte_unmap(dst_pte);
> -				src_pte = dst_pte = NULL;
> -				migration_entry_wait(mm, src_pmd, src_addr);
> -				ret = -EAGAIN;
> -			} else
> -				ret = -EFAULT;

Eww, good to get rid of this.

> +		if (softleaf_is_migration(entry)) {
> +			pte_unmap(src_pte);
> +			pte_unmap(dst_pte);
> +			src_pte = dst_pte = NULL;
> +			migration_entry_wait(mm, src_pmd, src_addr);
> +
> +			ret = -EAGAIN;
> +			goto out;
> +		} else if (!softleaf_is_swap(entry)) {
> +			ret = -EFAULT;
>  			goto out;
>  		}
>