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Date: Wed, 28 Feb 2024 11:31:50 +0100
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Subject: Re: [PATCH v5 6/8] mm: page_owner: add support for splitting to any
 order in split page_owner.
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To: Zi Yan <ziy@nvidia.com>, "Pankaj Raghav (Samsung)"
 <kernel@pankajraghav.com>, linux-mm@kvack.org
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>,
 Yang Shi <shy828301@gmail.com>, Yu Zhao <yuzhao@google.com>,
 "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
 Ryan Roberts <ryan.roberts@arm.com>, =?UTF-8?Q?Michal_Koutn=C3=BD?=
 <mkoutny@suse.com>, Roman Gushchin <roman.gushchin@linux.dev>,
 Zach O'Keefe <zokeefe@google.com>, Hugh Dickins <hughd@google.com>,
 Luis Chamberlain <mcgrof@kernel.org>,
 Andrew Morton <akpm@linux-foundation.org>, linux-kernel@vger.kernel.org,
 cgroups@vger.kernel.org, linux-fsdevel@vger.kernel.org,
 linux-kselftest@vger.kernel.org
References: <20240226205534.1603748-1-zi.yan@sent.com>
 <20240226205534.1603748-7-zi.yan@sent.com>
From: David Hildenbrand <david@redhat.com>
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Organization: Red Hat
In-Reply-To: <20240226205534.1603748-7-zi.yan@sent.com>
Content-Type: text/plain; charset=UTF-8; format=flowed
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On 26.02.24 21:55, Zi Yan wrote:
> From: Zi Yan <ziy@nvidia.com>
> 
> It adds a new_order parameter to set new page order in page owner.
> It prepares for upcoming changes to support split huge page to any
> lower order.
> 
> Signed-off-by: Zi Yan <ziy@nvidia.com>
> ---
>   include/linux/page_owner.h | 13 ++++++++-----
>   mm/huge_memory.c           |  2 +-
>   mm/page_alloc.c            |  4 ++--
>   mm/page_owner.c            |  7 +++----
>   4 files changed, 14 insertions(+), 12 deletions(-)
> 
> diff --git a/include/linux/page_owner.h b/include/linux/page_owner.h
> index 2b39c8e19d98..debdc25f08b9 100644
> --- a/include/linux/page_owner.h
> +++ b/include/linux/page_owner.h
> @@ -11,7 +11,8 @@ extern struct page_ext_operations page_owner_ops;
>   extern void __reset_page_owner(struct page *page, unsigned short order);
>   extern void __set_page_owner(struct page *page,
>   			unsigned short order, gfp_t gfp_mask);
> -extern void __split_page_owner(struct page *page, int order);
> +extern void __split_page_owner(struct page *page, int old_order,
> +			int new_order);
>   extern void __folio_copy_owner(struct folio *newfolio, struct folio *old);
>   extern void __set_page_owner_migrate_reason(struct page *page, int reason);
>   extern void __dump_page_owner(const struct page *page);
> @@ -31,10 +32,11 @@ static inline void set_page_owner(struct page *page,
>   		__set_page_owner(page, order, gfp_mask);
>   }
>   
> -static inline void split_page_owner(struct page *page, int order)
> +static inline void split_page_owner(struct page *page, int old_order,
> +			int new_order)
>   {
>   	if (static_branch_unlikely(&page_owner_inited))
> -		__split_page_owner(page, order);
> +		__split_page_owner(page, old_order, new_order);
>   }
>   static inline void folio_copy_owner(struct folio *newfolio, struct folio *old)
>   {
> @@ -56,10 +58,11 @@ static inline void reset_page_owner(struct page *page, unsigned short order)
>   {
>   }
>   static inline void set_page_owner(struct page *page,
> -			unsigned int order, gfp_t gfp_mask)
> +			unsigned short order, gfp_t gfp_mask)
>   {
>   }
> -static inline void split_page_owner(struct page *page, int order)
> +static inline void split_page_owner(struct page *page, int old_order,
> +			int new_order)
>   {
>   }
>   static inline void folio_copy_owner(struct folio *newfolio, struct folio *folio)
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index 5d4b7c17b9bc..b2df788c11fa 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -2933,7 +2933,7 @@ static void __split_huge_page(struct page *page, struct list_head *list,
>   	unlock_page_lruvec(lruvec);
>   	/* Caller disabled irqs, so they are still disabled here */
>   
> -	split_page_owner(head, order);
> +	split_page_owner(head, order, 0);
>   
>   	/* See comment in __split_huge_page_tail() */
>   	if (PageAnon(head)) {
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index c31a468fe317..cc41341c08f4 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -2652,7 +2652,7 @@ void split_page(struct page *page, unsigned int order)
>   
>   	for (i = 1; i < (1 << order); i++)
>   		set_page_refcounted(page + i);
> -	split_page_owner(page, order);
> +	split_page_owner(page, order, 0);
>   	split_page_memcg(page, order, 0);
>   }
>   EXPORT_SYMBOL_GPL(split_page);
> @@ -4839,7 +4839,7 @@ static void *make_alloc_exact(unsigned long addr, unsigned int order,
>   		struct page *page = virt_to_page((void *)addr);
>   		struct page *last = page + nr;
>   
> -		split_page_owner(page, order);
> +		split_page_owner(page, order, 0);
>   		split_page_memcg(page, order, 0);
>   		while (page < --last)
>   			set_page_refcounted(last);
> diff --git a/mm/page_owner.c b/mm/page_owner.c
> index b678f7a6e702..033e349f6479 100644
> --- a/mm/page_owner.c
> +++ b/mm/page_owner.c
> @@ -306,19 +306,18 @@ void __set_page_owner_migrate_reason(struct page *page, int reason)
>   	page_ext_put(page_ext);
>   }
>   
> -void __split_page_owner(struct page *page, int order)
> +void __split_page_owner(struct page *page, int old_order, int new_order)
>   {
>   	int i;
>   	struct page_ext *page_ext = page_ext_get(page);
>   	struct page_owner *page_owner;
> -	unsigned int nr = 1 << order;
>   
>   	if (unlikely(!page_ext))
>   		return;
>   
> -	for (i = 0; i < nr; i++) {
> +	for (i = 0; i < (1 << old_order); i++) {
>   		page_owner = get_page_owner(page_ext);
> -		page_owner->order = 0;
> +		page_owner->order = new_order;
>   		page_ext = page_ext_next(page_ext);
>   	}
>   	page_ext_put(page_ext);

Acked-by: David Hildenbrand <david@redhat.com>

-- 
Cheers,

David / dhildenb