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Message-ID: <48219ffc-62dc-430a-8055-6fb9ab533e7f@redhat.com>
Date: Wed, 14 Feb 2024 10:34:11 +0100
From: David Hildenbrand <david@...hat.com>
To: Zi Yan <ziy@...dia.com>, "Pankaj Raghav (Samsung)"
<kernel@...kajraghav.com>, linux-mm@...ck.org
Cc: "Matthew Wilcox (Oracle)" <willy@...radead.org>,
Yang Shi <shy828301@...il.com>, Yu Zhao <yuzhao@...gle.com>,
"Kirill A . Shutemov" <kirill.shutemov@...ux.intel.com>,
Ryan Roberts <ryan.roberts@....com>, Michal Koutný
<mkoutny@...e.com>, Roman Gushchin <roman.gushchin@...ux.dev>,
Zach O'Keefe <zokeefe@...gle.com>, Hugh Dickins <hughd@...gle.com>,
Mcgrof Chamberlain <mcgrof@...nel.org>,
Andrew Morton <akpm@...ux-foundation.org>, linux-kernel@...r.kernel.org,
cgroups@...r.kernel.org, linux-fsdevel@...r.kernel.org,
linux-kselftest@...r.kernel.org
Subject: Re: [PATCH v4 4/7] mm: page_owner: add support for splitting to any
order in split page_owner.
On 13.02.24 22:55, Zi Yan wrote:
> From: Zi Yan <ziy@...dia.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@...dia.com>
> ---
> include/linux/page_owner.h | 10 +++++-----
> mm/huge_memory.c | 2 +-
> mm/page_alloc.c | 4 ++--
> mm/page_owner.c | 9 +++++----
> 4 files changed, 13 insertions(+), 12 deletions(-)
>
> diff --git a/include/linux/page_owner.h b/include/linux/page_owner.h
> index d7878523adfc..a784ba69f67f 100644
> --- a/include/linux/page_owner.h
> +++ b/include/linux/page_owner.h
> @@ -11,7 +11,7 @@ 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 +31,10 @@ 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)
> {
> @@ -56,11 +56,11 @@ 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)
> + 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 3d30eccd3a7f..ad7133c97428 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -2919,7 +2919,7 @@ 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 9d4dd41d0647..e0f107b21c98 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);
> @@ -4837,7 +4837,7 @@ 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 1319e402c2cf..ebbffa0501db 100644
> --- a/mm/page_owner.c
> +++ b/mm/page_owner.c
> @@ -292,19 +292,20 @@ 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;
> + unsigned int old_nr = 1 << old_order;
> + unsigned int new_nr = 1 << new_order;
>
> if (unlikely(!page_ext))
> return;
>
> - for (i = 0; i < nr; i++) {
> + for (i = 0; i < old_nr; i += new_nr) {
> page_owner = get_page_owner(page_ext);
> - page_owner->order = 0;
> + page_owner->order = new_order;
> page_ext = page_ext_next(page_ext);
Staring at __set_page_owner_handle(), we do set all 1<<order page_exts
(corresponding to 1<<order "struct page"s) to have ->order set.
Wouldn't you have to do the same here?
for (i = 0; i < 1 << old_order; i++) {
page_owner = get_page_owner(page_ext);
page_owner->order = new_order;
page_ext = page_ext_next(page_ext);
}
--
Cheers,
David / dhildenb
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