linux-kernel - Re: [PATCH v2 2/8] hugetlb: no need to drop hugetlb_lock to call cma

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Date:   Mon, 29 Mar 2021 18:13:21 -0700
From:   Roman Gushchin <guro@...com>
To:     Mike Kravetz <mike.kravetz@...cle.com>
CC:     <linux-mm@...ck.org>, <linux-kernel@...r.kernel.org>,
        Michal Hocko <mhocko@...e.com>,
        Shakeel Butt <shakeelb@...gle.com>,
        Oscar Salvador <osalvador@...e.de>,
        David Hildenbrand <david@...hat.com>,
        Muchun Song <songmuchun@...edance.com>,
        David Rientjes <rientjes@...gle.com>,
        Miaohe Lin <linmiaohe@...wei.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Matthew Wilcox <willy@...radead.org>,
        HORIGUCHI NAOYA <naoya.horiguchi@....com>,
        "Aneesh Kumar K . V" <aneesh.kumar@...ux.ibm.com>,
        Waiman Long <longman@...hat.com>, Peter Xu <peterx@...hat.com>,
        Mina Almasry <almasrymina@...gle.com>,
        Hillf Danton <hdanton@...a.com>,
        Joonsoo Kim <iamjoonsoo.kim@....com>,
        Barry Song <song.bao.hua@...ilicon.com>,
        Will Deacon <will@...nel.org>,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH v2 2/8] hugetlb: no need to drop hugetlb_lock to call
 cma_release

On Mon, Mar 29, 2021 at 04:23:56PM -0700, Mike Kravetz wrote:
> Now that cma_release is non-blocking and irq safe, there is no need to
> drop hugetlb_lock before calling.
> 
> Signed-off-by: Mike Kravetz <mike.kravetz@...cle.com>
> ---
>  mm/hugetlb.c | 6 ------
>  1 file changed, 6 deletions(-)
> 
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 3c3e4baa4156..1d62f0492e7b 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1353,14 +1353,8 @@ static void update_and_free_page(struct hstate *h, struct page *page)
>  	set_compound_page_dtor(page, NULL_COMPOUND_DTOR);
>  	set_page_refcounted(page);
>  	if (hstate_is_gigantic(h)) {
> -		/*
> -		 * Temporarily drop the hugetlb_lock, because
> -		 * we might block in free_gigantic_page().
> -		 */
> -		spin_unlock(&hugetlb_lock);
>  		destroy_compound_gigantic_page(page, huge_page_order(h));
>  		free_gigantic_page(page, huge_page_order(h));
> -		spin_lock(&hugetlb_lock);
>  	} else {
>  		__free_pages(page, huge_page_order(h));
>  	}
> -- 
> 2.30.2
> 

Acked-by: Roman Gushchin <guro@...com>

Thanks!