linux-kernel - Re: [PATCH v2] mm/hugetlb: get rid of page

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Message-ID: <20230719230230.GB3240@monkey>
Date:   Wed, 19 Jul 2023 16:02:30 -0700
From:   Mike Kravetz <mike.kravetz@...cle.com>
To:     Sidhartha Kumar <sidhartha.kumar@...cle.com>
Cc:     linux-kernel@...r.kernel.org, linux-mm@...ck.org,
        akpm@...ux-foundation.org, songmuchun@...edance.com,
        willy@...radead.org
Subject: Re: [PATCH v2] mm/hugetlb: get rid of page_hstate()

On 07/19/23 11:41, Sidhartha Kumar wrote:
> Converts the last page_hstate() user to use folio_hstate() so
> page_hstate() can be safely removed.
> 
> Signed-off-by: Sidhartha Kumar <sidhartha.kumar@...cle.com>
> ---
> v1->v2:
> 	-change (page - &folio->page) to folio_page_idx(folio, page)
> 	 per Matthew Wilcox
> 
>  include/linux/hugetlb.h | 10 ----------
>  mm/hugetlb.c            |  6 +++---
>  mm/page_isolation.c     |  8 ++++----
>  3 files changed, 7 insertions(+), 17 deletions(-)

Thanks Sid and Matthew!

Reviewed-by: Mike Kravetz <mike.kravetz@...cle.com>
-- 
Mike Kravetz

> 
> diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
> index 9f4bac3df59e4..0a393bc02f25b 100644
> --- a/include/linux/hugetlb.h
> +++ b/include/linux/hugetlb.h
> @@ -841,11 +841,6 @@ static inline struct hstate *folio_hstate(struct folio *folio)
>  	return size_to_hstate(folio_size(folio));
>  }
>  
> -static inline struct hstate *page_hstate(struct page *page)
> -{
> -	return folio_hstate(page_folio(page));
> -}
> -
>  static inline unsigned hstate_index_to_shift(unsigned index)
>  {
>  	return hstates[index].order + PAGE_SHIFT;
> @@ -1062,11 +1057,6 @@ static inline struct hstate *folio_hstate(struct folio *folio)
>  	return NULL;
>  }
>  
> -static inline struct hstate *page_hstate(struct page *page)
> -{
> -	return NULL;
> -}
> -
>  static inline struct hstate *size_to_hstate(unsigned long size)
>  {
>  	return NULL;
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index e0028cbb86c09..154cc5b315727 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1812,10 +1812,10 @@ static void free_hpage_workfn(struct work_struct *work)
>  		node = node->next;
>  		page->mapping = NULL;
>  		/*
> -		 * The VM_BUG_ON_PAGE(!PageHuge(page), page) in page_hstate()
> -		 * is going to trigger because a previous call to
> +		 * The VM_BUG_ON_FOLIO(!folio_test_hugetlb(folio), folio) in
> +		 * folio_hstate() is going to trigger because a previous call to
>  		 * remove_hugetlb_folio() will call folio_set_compound_dtor
> -		 * (folio, NULL_COMPOUND_DTOR), so do not use page_hstate()
> +		 * (folio, NULL_COMPOUND_DTOR), so do not use folio_hstate()
>  		 * directly.

Looks like the code was updated in a commit prior to this comment change.
Thanks for updating the comment!

>  		 */
>  		h = size_to_hstate(page_size(page));
> diff --git a/mm/page_isolation.c b/mm/page_isolation.c
> index 6599cc965e216..bcf99ba747a05 100644
> --- a/mm/page_isolation.c
> +++ b/mm/page_isolation.c
> @@ -79,17 +79,17 @@ static struct page *has_unmovable_pages(unsigned long start_pfn, unsigned long e
>  		 * handle each tail page individually in migration.
>  		 */
>  		if (PageHuge(page) || PageTransCompound(page)) {
> -			struct page *head = compound_head(page);
> +			struct folio *folio = page_folio(page);
>  			unsigned int skip_pages;
>  
>  			if (PageHuge(page)) {
> -				if (!hugepage_migration_supported(page_hstate(head)))
> +				if (!hugepage_migration_supported(folio_hstate(folio)))
>  					return page;
> -			} else if (!PageLRU(head) && !__PageMovable(head)) {
> +			} else if (!folio_test_lru(folio) && !__folio_test_movable(folio)) {
>  				return page;
>  			}
>  
> -			skip_pages = compound_nr(head) - (page - head);
> +			skip_pages = folio_nr_pages(folio) - folio_page_idx(folio, page);
>  			pfn += skip_pages - 1;
>  			continue;
>  		}
> -- 
> 2.41.0
>