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Date:   Thu, 15 Apr 2021 13:41:54 +0200
From:   Michal Hocko <mhocko@suse.com>
To:     Oscar Salvador <osalvador@suse.de>
Cc:     Andrew Morton <akpm@linux-foundation.org>,
        Mike Kravetz <mike.kravetz@oracle.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        David Hildenbrand <david@redhat.com>,
        Muchun Song <songmuchun@bytedance.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Subject: Re: [PATCH v8 3/7] mm,hugetlb: Drop clearing of flag from
 prep_new_huge_page
Message-ID: <YHgmgtJRadMB2c5k@dhcp22.suse.cz>
References: <20210415103544.6791-1-osalvador@suse.de>
 <20210415103544.6791-4-osalvador@suse.de>
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In-Reply-To: <20210415103544.6791-4-osalvador@suse.de>
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On Thu 15-04-21 12:35:40, Oscar Salvador wrote:
> Pages allocated after boot get its private field cleared by means
> of post_alloc_hook().

You surely meant to say s@boot@page/cma allocator@ here

> Pages allocated during boot, that is directly from the memblock allocator,
> get cleared by paging_init()->..->memmap_init_zone->..->__init_single_page()
> before any memblock allocation.
> 
> Based on this ground, let us remove the clearing of the flag from
> prep_new_huge_page() as it is not needed.

I would also mention that this is a leftover from 6c0371490140
("hugetlb: convert PageHugeFreed to HPageFreed flag"). Previously the
explicit clearing was necessary because compound allocations do not get
this initialization (see prep_compound_page).

> Signed-off-by: Oscar Salvador <osalvador@suse.de>

with that
Acked-by: Michal Hocko <mhocko@suse.com>

> ---
>  mm/hugetlb.c | 1 -
>  1 file changed, 1 deletion(-)
> 
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 54d81d5947ed..2cb9fa79cbaa 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -1493,7 +1493,6 @@ static void prep_new_huge_page(struct hstate *h, struct page *page, int nid)
>  	spin_lock_irq(&hugetlb_lock);
>  	h->nr_huge_pages++;
>  	h->nr_huge_pages_node[nid]++;
> -	ClearHPageFreed(page);
>  	spin_unlock_irq(&hugetlb_lock);
>  }
>  
> -- 
> 2.16.3

-- 
Michal Hocko
SUSE Labs