Re: [PATCH 04/11] mm/hugetlb: unify hugetlb migration callback function

From: Roman Gushchin <guro@fb.com>
To: <js1304@gmail.com>
Cc: Andrew Morton <akpm@linux-foundation.org>, <linux-mm@kvack.org>,
	<linux-kernel@vger.kernel.org>, <kernel-team@lge.com>,
	Vlastimil Babka <vbabka@suse.cz>,
	Christoph Hellwig <hch@infradead.org>,
	Mike Kravetz <mike.kravetz@oracle.com>,
	Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>,
	Michal Hocko <mhocko@suse.com>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>
Subject: Re: [PATCH 04/11] mm/hugetlb: unify hugetlb migration callback function
Date: Wed, 20 May 2020 17:46:08 -0700	[thread overview]
Message-ID: <20200521004608.GC317575@carbon.dhcp.thefacebook.com> (raw)
In-Reply-To: <1589764857-6800-5-git-send-email-iamjoonsoo.kim@lge.com>

On Mon, May 18, 2020 at 10:20:50AM +0900, js1304@gmail.com wrote:
> From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> 
> There is no difference between two migration callback functions,
> alloc_huge_page_node() and alloc_huge_page_nodemask(), except
> __GFP_THISNODE handling. This patch adds one more field on to
> the alloc_control and handles this exception.
> 
> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> ---
>  include/linux/hugetlb.h |  8 --------
>  mm/hugetlb.c            | 23 ++---------------------
>  mm/internal.h           |  1 +
>  mm/mempolicy.c          |  3 ++-
>  4 files changed, 5 insertions(+), 30 deletions(-)
> 
> diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
> index 6da217e..4892ed3 100644
> --- a/include/linux/hugetlb.h
> +++ b/include/linux/hugetlb.h
> @@ -505,8 +505,6 @@ struct huge_bootmem_page {
>  
>  struct page *alloc_migrate_huge_page(struct hstate *h,
>  				struct alloc_control *ac);
> -struct page *alloc_huge_page_node(struct hstate *h,
> -				struct alloc_control *ac);
>  struct page *alloc_huge_page_nodemask(struct hstate *h,
>  				struct alloc_control *ac);

Maybe drop _nodemask suffix in the remaining function?

>  struct page *alloc_huge_page_vma(struct hstate *h, struct vm_area_struct *vma,
> @@ -755,12 +753,6 @@ static inline void huge_ptep_modify_prot_commit(struct vm_area_struct *vma,
>  struct hstate {};
>  
>  static inline struct page *
> -alloc_huge_page_node(struct hstate *h, struct alloc_control *ac)
> -{
> -	return NULL;
> -}
> -
> -static inline struct page *
>  alloc_huge_page_nodemask(struct hstate *h, struct alloc_control *ac)
>  {
>  	return NULL;
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 859dba4..60b0983 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1981,31 +1981,12 @@ struct page *alloc_buddy_huge_page_with_mpol(struct hstate *h,
>  }
>  
>  /* page migration callback function */
> -struct page *alloc_huge_page_node(struct hstate *h,
> -				struct alloc_control *ac)
> -{
> -	struct page *page = NULL;
> -
> -	ac->gfp_mask |= htlb_alloc_mask(h);
> -	if (ac->nid != NUMA_NO_NODE)
> -		ac->gfp_mask |= __GFP_THISNODE;
> -
> -	spin_lock(&hugetlb_lock);
> -	if (h->free_huge_pages - h->resv_huge_pages > 0)
> -		page = dequeue_huge_page_nodemask(h, ac);
> -	spin_unlock(&hugetlb_lock);
> -
> -	if (!page)
> -		page = alloc_migrate_huge_page(h, ac);
> -
> -	return page;
> -}
> -
> -/* page migration callback function */
>  struct page *alloc_huge_page_nodemask(struct hstate *h,
>  				struct alloc_control *ac)
>  {
>  	ac->gfp_mask |= htlb_alloc_mask(h);
> +	if (ac->thisnode && ac->nid != NUMA_NO_NODE)
> +		ac->gfp_mask |= __GFP_THISNODE;
>  
>  	spin_lock(&hugetlb_lock);
>  	if (h->free_huge_pages - h->resv_huge_pages > 0) {
> diff --git a/mm/internal.h b/mm/internal.h
> index 75b3f8e..574722d0 100644
> --- a/mm/internal.h
> +++ b/mm/internal.h
> @@ -618,6 +618,7 @@ struct alloc_control {
>  	int nid;
>  	nodemask_t *nmask;
>  	gfp_t gfp_mask;
> +	bool thisnode;
>  };

Can you, please, add some comments what each field exactly mean?

Thanks!

>  
>  #endif	/* __MM_INTERNAL_H */
> diff --git a/mm/mempolicy.c b/mm/mempolicy.c
> index 06f60a5..629feaa 100644
> --- a/mm/mempolicy.c
> +++ b/mm/mempolicy.c
> @@ -1073,9 +1073,10 @@ struct page *alloc_new_node_page(struct page *page, unsigned long node)
>  		struct alloc_control ac = {
>  			.nid = node,
>  			.nmask = NULL,
> +			.thisnode = true,
>  		};
>  
> -		return alloc_huge_page_node(h, &ac);
> +		return alloc_huge_page_nodemask(h, &ac);
>  	} else if (PageTransHuge(page)) {
>  		struct page *thp;
>  
> -- 
> 2.7.4
> 