linux-kernel - Re: [PATCH v4 8/9] mm/ksm: Convert chain series funcs and replace get_ksm

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Date: Tue, 9 Apr 2024 13:02:04 +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
Cc: Izik Eidus <izik.eidus@...ellosystems.com>,
 Matthew Wilcox <willy@...radead.org>, Andrea Arcangeli
 <aarcange@...hat.com>, Hugh Dickins <hughd@...gle.com>,
 Chris Wright <chrisw@...s-sol.org>
Subject: Re: [PATCH v4 8/9] mm/ksm: Convert chain series funcs and replace
 get_ksm_page

On 09.04.24 11:28, 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.
> 
> 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>
> Reviewed-by: David Hildenbrand <david@...hat.com>

I don't recall giving that yet :)

You could have kept some get_ksm_page()->ksm_get_folio() into a separate 
patch.

i.e., "[PATCH v3 11/14] mm/ksm: remove get_ksm_page and related info" 
from your old series could have mostly stayed separately.

[...]

>   /*
> @@ -1829,7 +1821,7 @@ static __always_inline struct page *chain(struct ksm_stable_node **s_n_d,
>    * This function returns the stable tree node of identical content if found,
>    * NULL otherwise.
>    */
> -static struct page *stable_tree_search(struct page *page)
> +static void *stable_tree_search(struct page *page)

There is one caller of stable_tree_search() in cmp_and_merge_page().

Why the change from page* to void* ?

I suspect cmp_and_merge_page() could similarly be converted to some 
degree to let kpage be a folio (separate patch).

-- 
Cheers,

David / dhildenb