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Subject: Re: [PATCH v8 4/7] mm,hugetlb: Split prep_new_huge_page functionality
To:     Oscar Salvador <osalvador@suse.de>,
        Andrew Morton <akpm@linux-foundation.org>
Cc:     Mike Kravetz <mike.kravetz@oracle.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        Michal Hocko <mhocko@kernel.org>,
        Muchun Song <songmuchun@bytedance.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, Michal Hocko <mhocko@suse.com>
References: <20210415103544.6791-1-osalvador@suse.de>
 <20210415103544.6791-5-osalvador@suse.de>
From:   David Hildenbrand <david@redhat.com>
Organization: Red Hat
Message-ID: <021eb32f-9664-8a1b-c3eb-9d51ca4fe21a@redhat.com>
Date:   Thu, 15 Apr 2021 14:42:20 +0200
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On 15.04.21 12:35, Oscar Salvador wrote:
> Currently, prep_new_huge_page() performs two functions.
> It sets the right state for a new hugetlb, and increases the hstate's
> counters to account for the new page.
> 
> Let us split its functionality into two separate functions, decoupling
> the handling of the counters from initializing a hugepage.
> The outcome is having __prep_new_huge_page(), which only
> initializes the page , and __prep_account_new_huge_page(), which adds
> the new page to the hstate's counters.
> 
> This allows us to be able to set a hugetlb without having to worry
> about the counter/locking. It will prove useful in the next patch.
> prep_new_huge_page() still calls both functions.
> 
> Signed-off-by: Oscar Salvador <osalvador@suse.de>
> Acked-by: Michal Hocko <mhocko@suse.com>
> Reviewed-by: Mike Kravetz <mike.kravetz@oracle.com>
> ---
>   mm/hugetlb.c | 20 +++++++++++++++++---
>   1 file changed, 17 insertions(+), 3 deletions(-)
> 
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 2cb9fa79cbaa..6f39ec79face 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1483,16 +1483,30 @@ void free_huge_page(struct page *page)
>   	}
>   }
>   
> -static void prep_new_huge_page(struct hstate *h, struct page *page, int nid)
> +/*
> + * Must be called with the hugetlb lock held
> + */
> +static void __prep_account_new_huge_page(struct hstate *h, int nid)
> +{
> +	lockdep_assert_held(&hugetlb_lock);
> +	h->nr_huge_pages++;
> +	h->nr_huge_pages_node[nid]++;
> +}
> +
> +static void __prep_new_huge_page(struct page *page)
>   {
>   	INIT_LIST_HEAD(&page->lru);
>   	set_compound_page_dtor(page, HUGETLB_PAGE_DTOR);
>   	hugetlb_set_page_subpool(page, NULL);
>   	set_hugetlb_cgroup(page, NULL);
>   	set_hugetlb_cgroup_rsvd(page, NULL);
> +}
> +
> +static void prep_new_huge_page(struct hstate *h, struct page *page, int nid)
> +{
> +	__prep_new_huge_page(page);
>   	spin_lock_irq(&hugetlb_lock);
> -	h->nr_huge_pages++;
> -	h->nr_huge_pages_node[nid]++;
> +	__prep_account_new_huge_page(h, nid);
>   	spin_unlock_irq(&hugetlb_lock);
>   }
>   
> 

Reviewed-by: David Hildenbrand <david@redhat.com>

-- 
Thanks,

David / dhildenb