linux-kernel - Re: [PATCH v2 13/14] mm/ksm: use folio_set_stable_node in try_to_merge_one

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Message-ID: <Zf5OvWFiYjs_ZCF2@casper.infradead.org>
Date: Sat, 23 Mar 2024 03:38:37 +0000
From: Matthew Wilcox <willy@...radead.org>
To: alexs@...nel.org
Cc: Andrea Arcangeli <aarcange@...hat.com>,
	Izik Eidus <izik.eidus@...ellosystems.com>, david@...hat.com,
	Andrew Morton <akpm@...ux-foundation.org>, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org, Hugh Dickins <hughd@...gle.com>,
	Chris Wright <chrisw@...s-sol.org>
Subject: Re: [PATCH v2 13/14] mm/ksm: use folio_set_stable_node in
 try_to_merge_one_page

On Fri, Mar 22, 2024 at 04:37:00PM +0800, alexs@...nel.org wrote:
> From: "Alex Shi (tencent)" <alexs@...nel.org>
> 
> Only single page could be reached where we set stable node after write
> protect, so use folio converted func to replace page's.
> 
> Signed-off-by: Alex Shi (tencent) <alexs@...nel.org>
> Cc: Izik Eidus <izik.eidus@...ellosystems.com>
> Cc: Matthew Wilcox <willy@...radead.org>
> Cc: Andrea Arcangeli <aarcange@...hat.com>
> Cc: Hugh Dickins <hughd@...gle.com>
> Cc: Chris Wright <chrisw@...s-sol.org>
> ---
>  mm/ksm.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/mm/ksm.c b/mm/ksm.c
> index 15a78a9bab59..d7c4cc4a0cc1 100644
> --- a/mm/ksm.c
> +++ b/mm/ksm.c
> @@ -1518,7 +1518,7 @@ static int try_to_merge_one_page(struct vm_area_struct *vma,
>  			 * PageAnon+anon_vma to PageKsm+NULL stable_node:
>  			 * stable_tree_insert() will update stable_node.
>  			 */
> -			set_page_stable_node(page, NULL);
> +			folio_set_stable_node(page_folio(page), NULL);
>  			mark_page_accessed(page);

I'd rather you did a conversion of try_to_merge_one_page() instead of
just this.  It'll be a fun one because you'll have to recalculate the
folio after calling split_huge_page().