Re: [PATCH 3/6] mm/page_owner: Constify dump_page_owner

[Vlastimil Babka]

On 4/17/21 1:15 AM, Matthew Wilcox (Oracle) wrote:
> dump_page_owner() only uses struct page to find the page_ext, and
> lookup_page_ext() already takes a const argument.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>

Reviewed-by: Vlastimil Babka <vbabka@xxxxxxx>

> ---
>  include/linux/page_owner.h | 6 +++---
>  mm/page_owner.c            | 2 +-
>  2 files changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/include/linux/page_owner.h b/include/linux/page_owner.h
> index 3468794f83d2..719bfe5108c5 100644
> --- a/include/linux/page_owner.h
> +++ b/include/linux/page_owner.h
> @@ -14,7 +14,7 @@ extern void __set_page_owner(struct page *page,
>  extern void __split_page_owner(struct page *page, unsigned int nr);
>  extern void __copy_page_owner(struct page *oldpage, struct page *newpage);
>  extern void __set_page_owner_migrate_reason(struct page *page, int reason);
> -extern void __dump_page_owner(struct page *page);
> +extern void __dump_page_owner(const struct page *page);
>  extern void pagetypeinfo_showmixedcount_print(struct seq_file *m,
>  					pg_data_t *pgdat, struct zone *zone);
>  
> @@ -46,7 +46,7 @@ static inline void set_page_owner_migrate_reason(struct page *page, int reason)
>  	if (static_branch_unlikely(&page_owner_inited))
>  		__set_page_owner_migrate_reason(page, reason);
>  }
> -static inline void dump_page_owner(struct page *page)
> +static inline void dump_page_owner(const struct page *page)
>  {
>  	if (static_branch_unlikely(&page_owner_inited))
>  		__dump_page_owner(page);
> @@ -69,7 +69,7 @@ static inline void copy_page_owner(struct page *oldpage, struct page *newpage)
>  static inline void set_page_owner_migrate_reason(struct page *page, int reason)
>  {
>  }
> -static inline void dump_page_owner(struct page *page)
> +static inline void dump_page_owner(const struct page *page)
>  {
>  }
>  #endif /* CONFIG_PAGE_OWNER */
> diff --git a/mm/page_owner.c b/mm/page_owner.c
> index adfabb560eb9..f51a57e92aa3 100644
> --- a/mm/page_owner.c
> +++ b/mm/page_owner.c
> @@ -392,7 +392,7 @@ print_page_owner(char __user *buf, size_t count, unsigned long pfn,
>  	return -ENOMEM;
>  }
>  
> -void __dump_page_owner(struct page *page)
> +void __dump_page_owner(const struct page *page)
>  {
>  	struct page_ext *page_ext = lookup_page_ext(page);
>  	struct page_owner *page_owner;
>