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Date:   Fri, 6 Jan 2023 16:30:54 -0800
From:   Mike Kravetz <mike.kravetz@oracle.com>
To:     Sidhartha Kumar <sidhartha.kumar@oracle.com>
Cc:     linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        akpm@linux-foundation.org, songmuchun@bytedance.com,
        willy@infradead.org, tsahu@linux.ibm.com, jhubbard@nvidia.com
Subject: Re: [PATCH mm-unstable 5/8] mm/hugetlb: increase use of folios in
 alloc_huge_page()
Message-ID: <Y7i9Php73/tzU2a1@monkey>
References: <20230103191340.116536-1-sidhartha.kumar@oracle.com>
 <20230103191340.116536-6-sidhartha.kumar@oracle.com>
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On 01/03/23 13:13, Sidhartha Kumar wrote:
> Change hugetlb_cgroup_commit_charge{,_rsvd}(), dequeue_huge_page_vma()
> and alloc_buddy_huge_page_with_mpol() to use folios

Nice that the only 'conversion' was to eliminate the page to folio or
folio to page calls in those routines.

>                                                     so alloc_huge_page()
> is cleaned by operating on folios until its return.
> 
> Signed-off-by: Sidhartha Kumar <sidhartha.kumar@oracle.com>
> ---
>  include/linux/hugetlb_cgroup.h |  8 ++++----
>  mm/hugetlb.c                   | 33 ++++++++++++++++-----------------
>  mm/hugetlb_cgroup.c            |  8 ++------
>  3 files changed, 22 insertions(+), 27 deletions(-)

Thanks,

Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
-- 
Mike Kravetz
> 
> diff --git a/include/linux/hugetlb_cgroup.h b/include/linux/hugetlb_cgroup.h
> index f706626a8063..3d82d91f49ac 100644
> --- a/include/linux/hugetlb_cgroup.h
> +++ b/include/linux/hugetlb_cgroup.h
> @@ -141,10 +141,10 @@ extern int hugetlb_cgroup_charge_cgroup_rsvd(int idx, unsigned long nr_pages,
>  					     struct hugetlb_cgroup **ptr);
>  extern void hugetlb_cgroup_commit_charge(int idx, unsigned long nr_pages,
>  					 struct hugetlb_cgroup *h_cg,
> -					 struct page *page);
> +					 struct folio *folio);
>  extern void hugetlb_cgroup_commit_charge_rsvd(int idx, unsigned long nr_pages,
>  					      struct hugetlb_cgroup *h_cg,
> -					      struct page *page);
> +					      struct folio *folio);
>  extern void hugetlb_cgroup_uncharge_folio(int idx, unsigned long nr_pages,
>  					 struct folio *folio);
>  extern void hugetlb_cgroup_uncharge_folio_rsvd(int idx, unsigned long nr_pages,
> @@ -230,14 +230,14 @@ static inline int hugetlb_cgroup_charge_cgroup_rsvd(int idx,
>  
>  static inline void hugetlb_cgroup_commit_charge(int idx, unsigned long nr_pages,
>  						struct hugetlb_cgroup *h_cg,
> -						struct page *page)
> +						struct folio *folio)
>  {
>  }
>  
>  static inline void
>  hugetlb_cgroup_commit_charge_rsvd(int idx, unsigned long nr_pages,
>  				  struct hugetlb_cgroup *h_cg,
> -				  struct page *page)
> +				  struct folio *folio)
>  {
>  }
>  
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 0b8bab52bc7e..640ca4eaccf2 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1209,7 +1209,7 @@ static unsigned long available_huge_pages(struct hstate *h)
>  	return h->free_huge_pages - h->resv_huge_pages;
>  }
>  
> -static struct page *dequeue_huge_page_vma(struct hstate *h,
> +static struct folio *dequeue_hugetlb_folio_vma(struct hstate *h,
>  				struct vm_area_struct *vma,
>  				unsigned long address, int avoid_reserve,
>  				long chg)
> @@ -1253,7 +1253,7 @@ static struct page *dequeue_huge_page_vma(struct hstate *h,
>  	}
>  
>  	mpol_cond_put(mpol);
> -	return &folio->page;
> +	return folio;
>  
>  err:
>  	return NULL;
> @@ -2305,7 +2305,7 @@ static struct page *alloc_migrate_huge_page(struct hstate *h, gfp_t gfp_mask,
>   * Use the VMA's mpolicy to allocate a huge page from the buddy.
>   */
>  static
> -struct page *alloc_buddy_huge_page_with_mpol(struct hstate *h,
> +struct folio *alloc_buddy_hugetlb_folio_with_mpol(struct hstate *h,
>  		struct vm_area_struct *vma, unsigned long addr)
>  {
>  	struct folio *folio = NULL;
> @@ -2328,7 +2328,7 @@ struct page *alloc_buddy_huge_page_with_mpol(struct hstate *h,
>  	if (!folio)
>  		folio = alloc_surplus_hugetlb_folio(h, gfp_mask, nid, nodemask);
>  	mpol_cond_put(mpol);
> -	return &folio->page;
> +	return folio;
>  }
>  
>  /* page migration callback function */
> @@ -2877,7 +2877,6 @@ struct page *alloc_huge_page(struct vm_area_struct *vma,
>  {
>  	struct hugepage_subpool *spool = subpool_vma(vma);
>  	struct hstate *h = hstate_vma(vma);
> -	struct page *page;
>  	struct folio *folio;
>  	long map_chg, map_commit;
>  	long gbl_chg;
> @@ -2941,34 +2940,34 @@ struct page *alloc_huge_page(struct vm_area_struct *vma,
>  	 * from the global free pool (global change).  gbl_chg == 0 indicates
>  	 * a reservation exists for the allocation.
>  	 */
> -	page = dequeue_huge_page_vma(h, vma, addr, avoid_reserve, gbl_chg);
> -	if (!page) {
> +	folio = dequeue_hugetlb_folio_vma(h, vma, addr, avoid_reserve, gbl_chg);
> +	if (!folio) {
>  		spin_unlock_irq(&hugetlb_lock);
> -		page = alloc_buddy_huge_page_with_mpol(h, vma, addr);
> -		if (!page)
> +		folio = alloc_buddy_hugetlb_folio_with_mpol(h, vma, addr);
> +		if (!folio)
>  			goto out_uncharge_cgroup;
>  		spin_lock_irq(&hugetlb_lock);
>  		if (!avoid_reserve && vma_has_reserves(vma, gbl_chg)) {
> -			SetHPageRestoreReserve(page);
> +			folio_set_hugetlb_restore_reserve(folio);
>  			h->resv_huge_pages--;
>  		}
> -		list_add(&page->lru, &h->hugepage_activelist);
> -		set_page_refcounted(page);
> +		list_add(&folio->lru, &h->hugepage_activelist);
> +		folio_ref_unfreeze(folio, 1);
>  		/* Fall through */
>  	}
> -	folio = page_folio(page);
> -	hugetlb_cgroup_commit_charge(idx, pages_per_huge_page(h), h_cg, page);
> +
> +	hugetlb_cgroup_commit_charge(idx, pages_per_huge_page(h), h_cg, folio);
>  	/* If allocation is not consuming a reservation, also store the
>  	 * hugetlb_cgroup pointer on the page.
>  	 */
>  	if (deferred_reserve) {
>  		hugetlb_cgroup_commit_charge_rsvd(idx, pages_per_huge_page(h),
> -						  h_cg, page);
> +						  h_cg, folio);
>  	}
>  
>  	spin_unlock_irq(&hugetlb_lock);
>  
> -	hugetlb_set_page_subpool(page, spool);
> +	hugetlb_set_folio_subpool(folio, spool);
>  
>  	map_commit = vma_commit_reservation(h, vma, addr);
>  	if (unlikely(map_chg > map_commit)) {
> @@ -2989,7 +2988,7 @@ struct page *alloc_huge_page(struct vm_area_struct *vma,
>  			hugetlb_cgroup_uncharge_folio_rsvd(hstate_index(h),
>  					pages_per_huge_page(h), folio);
>  	}
> -	return page;
> +	return &folio->page;
>  
>  out_uncharge_cgroup:
>  	hugetlb_cgroup_uncharge_cgroup(idx, pages_per_huge_page(h), h_cg);
> diff --git a/mm/hugetlb_cgroup.c b/mm/hugetlb_cgroup.c
> index d9e4425d81ac..dedd2edb076e 100644
> --- a/mm/hugetlb_cgroup.c
> +++ b/mm/hugetlb_cgroup.c
> @@ -331,19 +331,15 @@ static void __hugetlb_cgroup_commit_charge(int idx, unsigned long nr_pages,
>  
>  void hugetlb_cgroup_commit_charge(int idx, unsigned long nr_pages,
>  				  struct hugetlb_cgroup *h_cg,
> -				  struct page *page)
> +				  struct folio *folio)
>  {
> -	struct folio *folio = page_folio(page);
> -
>  	__hugetlb_cgroup_commit_charge(idx, nr_pages, h_cg, folio, false);
>  }
>  
>  void hugetlb_cgroup_commit_charge_rsvd(int idx, unsigned long nr_pages,
>  				       struct hugetlb_cgroup *h_cg,
> -				       struct page *page)
> +				       struct folio *folio)
>  {
> -	struct folio *folio = page_folio(page);
> -
>  	__hugetlb_cgroup_commit_charge(idx, nr_pages, h_cg, folio, true);
>  }
>  
> -- 
> 2.39.0
>