linux-kernel - Re: [RFC PATCH 2/4] mm/page_isolation: remove migratetype from move_freepages_block

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Message-ID: <8f9f16e9-4d89-44ba-a244-9389233b5325@redhat.com>
Date: Mon, 2 Sep 2024 16:42:22 +0200
From: David Hildenbrand <david@...hat.com>
To: Zi Yan <ziy@...dia.com>, linux-mm@...ck.org
Cc: Oscar Salvador <osalvador@...e.de>, Vlastimil Babka <vbabka@...e.cz>,
 Johannes Weiner <hannes@...xchg.org>,
 Baolin Wang <baolin.wang@...ux.alibaba.com>,
 "Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
 Mel Gorman <mgorman@...e.de>, linux-kernel@...r.kernel.org
Subject: Re: [RFC PATCH 2/4] mm/page_isolation: remove migratetype from
 move_freepages_block_isolate()

On 28.08.24 22:22, Zi Yan wrote:
> Since migratetype is no longer overwritten during pageblock isolation,
> moving pageblocks to and from MIGRATE_ISOLATE do not need migratetype.
> 
> Signed-off-by: Zi Yan <ziy@...dia.com>
> ---
>   include/linux/page-isolation.h |  3 +--
>   mm/page_alloc.c                | 27 +++++++++++++++++++++------
>   mm/page_isolation.c            | 19 +++++++++----------
>   3 files changed, 31 insertions(+), 18 deletions(-)
> 
> diff --git a/include/linux/page-isolation.h b/include/linux/page-isolation.h
> index 11b8695115ea..6a62401410c3 100644
> --- a/include/linux/page-isolation.h
> +++ b/include/linux/page-isolation.h
> @@ -35,8 +35,7 @@ static inline bool is_migrate_isolate(int migratetype)
>   
>   void set_pageblock_migratetype(struct page *page, int migratetype);
>   
> -bool move_freepages_block_isolate(struct zone *zone, struct page *page,
> -				  int migratetype);
> +bool move_freepages_block_isolate(struct zone *zone, struct page *page);
>   
>   int start_isolate_page_range(unsigned long start_pfn, unsigned long end_pfn,
>   			     int migratetype, int flags, gfp_t gfp_flags);
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 4ea5cd1a07e2..dc7c36461953 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -1764,10 +1764,12 @@ static unsigned long find_large_buddy(unsigned long start_pfn)
>    *
>    * Returns %true if pages could be moved, %false otherwise.
>    */
> -bool move_freepages_block_isolate(struct zone *zone, struct page *page,
> -				  int migratetype)
> +bool move_freepages_block_isolate(struct zone *zone, struct page *page)
>   {
>   	unsigned long start_pfn, pfn;
> +	bool is_block_isolated = get_pageblock_isolate(page);
> +	int from_mt;

I think we should have two functions, one that isolates, another one 
that un-isolates. Or at least make the semantics not depend on the 
current state of the pageblock.

bool pageblock_set_isolated_and_move_free_pages(struct zone *zone, 
struct page *page, bool isolated);

vs.

pageblock_isolate_and_move_free_pages()
pageblock_unisolate_and_move_free_pages()

-- 
Cheers,

David / dhildenb