linux-kernel - Re: [PATCH V3] mm/hugetlb: add available_huge

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Date:   Mon, 19 Sep 2022 16:58:53 -0700
From:   Mike Kravetz <mike.kravetz@...cle.com>
To:     Xin Hao <xhao@...ux.alibaba.com>
Cc:     songmuchun@...edance.com, akpm@...ux-foundation.org,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V3] mm/hugetlb: add available_huge_pages() func

On 09/17/22 09:15, Xin Hao wrote:
> In hugetlb.c file, there are several places to compare the values of
> 'h->free_huge_pages' and 'h->resv_huge_pages', it looks a bit messy, so
> there add a new available_huge_pages() func to do these.

Thanks, I think the code looks a little better with this change.

> 
> Signed-off-by: Xin Hao <xhao@...ux.alibaba.com>
> Changes from v2
> https://lore.kernel.org/linux-mm/20220916064127.1904-1-xhao@linux.alibaba.com/
> - Convert is_resv_equal_free() to available_huge_pages()

I believe the above 'Changes from v2' information should be below the marker
'---' as it will not be included in the changelog.

> ---
>  mm/hugetlb.c | 14 +++++++++-----
>  1 file changed, 9 insertions(+), 5 deletions(-)

The changes look fine,

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

> 
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 5ea0b1b0d1ab..21d7f2361696 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1191,6 +1191,11 @@ static struct page *dequeue_huge_page_nodemask(struct hstate *h, gfp_t gfp_mask,
>  	return NULL;
>  }
> 
> +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,
>  				struct vm_area_struct *vma,
>  				unsigned long address, int avoid_reserve,
> @@ -1207,12 +1212,11 @@ static struct page *dequeue_huge_page_vma(struct hstate *h,
>  	 * have no page reserves. This check ensures that reservations are
>  	 * not "stolen". The child may still get SIGKILLed
>  	 */
> -	if (!vma_has_reserves(vma, chg) &&
> -			h->free_huge_pages - h->resv_huge_pages == 0)
> +	if (!vma_has_reserves(vma, chg) && !available_huge_pages(h))
>  		goto err;
> 
>  	/* If reserves cannot be used, ensure enough pages are in the pool */
> -	if (avoid_reserve && h->free_huge_pages - h->resv_huge_pages == 0)
> +	if (avoid_reserve && !available_huge_pages(h))
>  		goto err;
> 
>  	gfp_mask = htlb_alloc_mask(h);
> @@ -2105,7 +2109,7 @@ int dissolve_free_huge_page(struct page *page)
>  	if (!page_count(page)) {
>  		struct page *head = compound_head(page);
>  		struct hstate *h = page_hstate(head);
> -		if (h->free_huge_pages - h->resv_huge_pages == 0)
> +		if (!available_huge_pages(h))
>  			goto out;
> 
>  		/*
> @@ -2315,7 +2319,7 @@ struct page *alloc_huge_page_nodemask(struct hstate *h, int preferred_nid,
>  		nodemask_t *nmask, gfp_t gfp_mask)
>  {
>  	spin_lock_irq(&hugetlb_lock);
> -	if (h->free_huge_pages - h->resv_huge_pages > 0) {
> +	if (available_huge_pages(h)) {
>  		struct page *page;
> 
>  		page = dequeue_huge_page_nodemask(h, gfp_mask, preferred_nid, nmask);
> --
> 2.31.0