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Subject: Re: [PATCH] hugetlb: document the new location of page subpool
 pointer
To:     Mike Kravetz <mike.kravetz@oracle.com>,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org
Cc:     Michal Hocko <mhocko@suse.com>, Oscar Salvador <osalvador@suse.de>,
        Muchun Song <songmuchun@bytedance.com>,
        Andrew Morton <akpm@linux-foundation.org>
References: <20210223180820.ee39f1544f2630d0eecf3a57@linux-foundation.org>
 <20210224040439.351882-1-mike.kravetz@oracle.com>
From:   David Hildenbrand <david@redhat.com>
Organization: Red Hat GmbH
Message-ID: <c34d52f9-1e77-7ed4-2209-df8af9f2e96d@redhat.com>
Date:   Wed, 24 Feb 2021 11:06:39 +0100
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On 24.02.21 05:04, Mike Kravetz wrote:
> Expand comments, no functional change.
> 
> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
> ---
>   include/linux/hugetlb.h | 3 +++
>   1 file changed, 3 insertions(+)
> 
> diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
> index cccd1aab69dd..c0467a7a1fe0 100644
> --- a/include/linux/hugetlb.h
> +++ b/include/linux/hugetlb.h
> @@ -476,6 +476,9 @@ unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
>    * huegtlb page specific state flags.  These flags are located in page.private
>    * of the hugetlb head page.  Functions created via the below macros should be
>    * used to manipulate these flags.
> + * Note: The hugetlb page subpool pointer previously located at page.private
> + * was moved to page[1].private to make room for flags in the head page.  See
> + * hugetlb_page_subpool().
>    *
>    * HPG_restore_reserve - Set when a hugetlb page consumes a reservation at
>    *	allocation time.  Cleared when page is fully instantiated.  Free
> 

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

-- 
Thanks,

David / dhildenb