Re: [PATCHv2] mm/page_alloc: Make deferred page init free pages in MAX_ORDER blocks

[Mike Rapoport <rppt@kernel.org>]

On Tue, Mar 21, 2023 at 03:24:15AM +0300, Kirill A. Shutemov wrote:
> Normal page init path frees pages during the boot in MAX_ORDER chunks,
> but deferred page init path does it in pageblock blocks.
> 
> Change deferred page init path to work in MAX_ORDER blocks.
> 
> For cases when MAX_ORDER is larger than pageblock, set migrate type to
> MIGRATE_MOVABLE for all pageblocks covered by the page.
> 
> Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>

Acked-by: Mike Rapoport (IBM) <rppt@kernel.org>

> ---
> 
> Note: the patch depends on the new definiton of MAX_ORDER.
> 
> v2:
> 
>  - Fix commit message;
> 
> ---
>  include/linux/mmzone.h |  2 ++
>  mm/page_alloc.c        | 19 ++++++++++---------
>  2 files changed, 12 insertions(+), 9 deletions(-)
> 
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index 96599cb9eb62..f53fe3a7ca45 100644
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -32,6 +32,8 @@
>  #endif
>  #define MAX_ORDER_NR_PAGES (1 << MAX_ORDER)
>  
> +#define IS_MAX_ORDER_ALIGNED(pfn) IS_ALIGNED(pfn, MAX_ORDER_NR_PAGES)
> +
>  /*
>   * PAGE_ALLOC_COSTLY_ORDER is the order at which allocations are deemed
>   * costly to service.  That is between allocation orders which should
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 87d760236dba..fc02a243425d 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -1875,9 +1875,10 @@ static void __init deferred_free_range(unsigned long pfn,
>  	page = pfn_to_page(pfn);
>  
>  	/* Free a large naturally-aligned chunk if possible */
> -	if (nr_pages == pageblock_nr_pages && pageblock_aligned(pfn)) {
> -		set_pageblock_migratetype(page, MIGRATE_MOVABLE);
> -		__free_pages_core(page, pageblock_order);
> +	if (nr_pages == MAX_ORDER_NR_PAGES && IS_MAX_ORDER_ALIGNED(pfn)) {
> +		for (i = 0; i < nr_pages; i += pageblock_nr_pages)
> +			set_pageblock_migratetype(page + i, MIGRATE_MOVABLE);
> +		__free_pages_core(page, MAX_ORDER);
>  		return;
>  	}
>  
> @@ -1901,19 +1902,19 @@ static inline void __init pgdat_init_report_one_done(void)
>  /*
>   * Returns true if page needs to be initialized or freed to buddy allocator.
>   *
> - * We check if a current large page is valid by only checking the validity
> + * We check if a current MAX_ORDER block is valid by only checking the validity
>   * of the head pfn.
>   */
>  static inline bool __init deferred_pfn_valid(unsigned long pfn)
>  {
> -	if (pageblock_aligned(pfn) && !pfn_valid(pfn))
> +	if (IS_MAX_ORDER_ALIGNED(pfn) && !pfn_valid(pfn))
>  		return false;
>  	return true;
>  }
>  
>  /*
>   * Free pages to buddy allocator. Try to free aligned pages in
> - * pageblock_nr_pages sizes.
> + * MAX_ORDER_NR_PAGES sizes.
>   */
>  static void __init deferred_free_pages(unsigned long pfn,
>  				       unsigned long end_pfn)
> @@ -1924,7 +1925,7 @@ static void __init deferred_free_pages(unsigned long pfn,
>  		if (!deferred_pfn_valid(pfn)) {
>  			deferred_free_range(pfn - nr_free, nr_free);
>  			nr_free = 0;
> -		} else if (pageblock_aligned(pfn)) {
> +		} else if (IS_MAX_ORDER_ALIGNED(pfn)) {
>  			deferred_free_range(pfn - nr_free, nr_free);
>  			nr_free = 1;
>  		} else {
> @@ -1937,7 +1938,7 @@ static void __init deferred_free_pages(unsigned long pfn,
>  
>  /*
>   * Initialize struct pages.  We minimize pfn page lookups and scheduler checks
> - * by performing it only once every pageblock_nr_pages.
> + * by performing it only once every MAX_ORDER_NR_PAGES.
>   * Return number of pages initialized.
>   */
>  static unsigned long  __init deferred_init_pages(struct zone *zone,
> @@ -1953,7 +1954,7 @@ static unsigned long  __init deferred_init_pages(struct zone *zone,
>  		if (!deferred_pfn_valid(pfn)) {
>  			page = NULL;
>  			continue;
> -		} else if (!page || pageblock_aligned(pfn)) {
> +		} else if (!page || IS_MAX_ORDER_ALIGNED(pfn)) {
>  			page = pfn_to_page(pfn);
>  		} else {
>  			page++;
> -- 
> 2.39.2
> 

-- 
Sincerely yours,
Mike.