linux-kernel - Re: [PATCH v5 08/10] mm/ksm: Convert chain series funcs and replace get_ksm

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Date: Thu, 11 Apr 2024 09:53:01 +0200
From: David Hildenbrand <david@...hat.com>
To: alexs@...nel.org, Andrew Morton <akpm@...ux-foundation.org>,
 linux-mm@...ck.org, linux-kernel@...r.kernel.org,
 zik.eidus@...ellosystems.com, willy@...radead.org, aarcange@...hat.com,
 hughd@...gle.com, chrisw@...s-sol.org
Cc: Izik Eidus <izik.eidus@...ellosystems.com>
Subject: Re: [PATCH v5 08/10] mm/ksm: Convert chain series funcs and replace
 get_ksm_page

On 11.04.24 08:17, alexs@...nel.org wrote:
> From: "Alex Shi (tencent)" <alexs@...nel.org>
> 
> In ksm stable tree all page are single, let's convert them to use and
> folios as well as stable_tree_insert/stable_tree_search funcs.
> And replace get_ksm_page() by ksm_get_folio() since there is no more
> needs.
> 
> It could save a few compound_head calls.
> 
> 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>
> Signed-off-by: Alex Shi (tencent) <alexs@...nel.org>
> ---

Nit: "mm/ksm: convert ..." so in your series all start lowercase :)

[...]

> @@ -3244,7 +3238,7 @@ void folio_migrate_ksm(struct folio *newfolio, struct folio *folio)
>   		/*
>   		 * newfolio->mapping was set in advance; now we need smp_wmb()
>   		 * to make sure that the new stable_node->kpfn is visible
> -		 * to get_ksm_page() before it can see that folio->mapping
> +		 * to ksm_get_folio() before it can see that folio->mapping
>   		 * has gone stale (or that folio_test_swapcache has been cleared).
>   		 */
>   		smp_wmb();
> @@ -3271,7 +3265,7 @@ static bool stable_node_dup_remove_range(struct ksm_stable_node *stable_node,
>   	if (stable_node->kpfn >= start_pfn &&
>   	    stable_node->kpfn < end_pfn) {
>   		/*
> -		 * Don't get_ksm_page, page has already gone:
> +		 * Don't ksm_get_folio, page has already gone:
>   		 * which is why we keep kpfn instead of page*
>   		 */
>   		remove_node_from_stable_tree(stable_node);
> @@ -3359,7 +3353,7 @@ static int ksm_memory_callback(struct notifier_block *self,
>   		 * Most of the work is done by page migration; but there might
>   		 * be a few stable_nodes left over, still pointing to struct
>   		 * pages which have been offlined: prune those from the tree,
> -		 * otherwise get_ksm_page() might later try to access a
> +		 * otherwise ksm_get_folio() might later try to access a
>   		 * non-existent struct page.
>   		 */
>   		ksm_check_stable_tree(mn->start_pfn,
> diff --git a/mm/migrate.c b/mm/migrate.c
> index 73a052a382f1..9f0494fd902c 100644
> --- a/mm/migrate.c
> +++ b/mm/migrate.c
> @@ -616,7 +616,7 @@ void folio_migrate_flags(struct folio *newfolio, struct folio *folio)
>   	folio_migrate_ksm(newfolio, folio);
>   	/*
>   	 * Please do not reorder this without considering how mm/ksm.c's
> -	 * get_ksm_page() depends upon ksm_migrate_page() and PageSwapCache().
> +	 * ksm_get_folio() depends upon ksm_migrate_page() and PageSwapCache().
>   	 */
>   	if (folio_test_swapcache(folio))
>   		folio_clear_swapcache(folio);

I'd have moved these 3 into a separate patch, but fine with me

Reviewed-by: David Hildenbrand <david@...hat.com>

-- 
Cheers,

David / dhildenb