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Subject: Re: [v2 PATCH] mm: thp: handle page cache THP correctly in
 PageTransCompoundMap
To:     Matthew Wilcox <willy@infradead.org>
Cc:     hughd@google.com, aarcange@redhat.com,
        kirill.shutemov@linux.intel.com, gavin.dg@linux.alibaba.com,
        akpm@linux-foundation.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, stable@vger.kernel.org
References: <1571850304-82802-1-git-send-email-yang.shi@linux.alibaba.com>
 <20191023172420.GB2963@bombadil.infradead.org>
From:   Yang Shi <yang.shi@linux.alibaba.com>
Message-ID: <792ea136-4fa0-c87b-9399-5ca47c501c9c@linux.alibaba.com>
Date:   Wed, 23 Oct 2019 10:57:44 -0700
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On 10/23/19 10:24 AM, Matthew Wilcox wrote:
> On Thu, Oct 24, 2019 at 01:05:04AM +0800, Yang Shi wrote:
>> +	return map_count >= 0 &&
>> +	       map_count == atomic_read(&head[1].compound_mapcount);
>>   }
> I didn't like Hugh's duplicate definition either.  May I suggest:

Thanks, Willy. It is fine to me. Will take it in v3.

>
> diff --git a/include/linux/mm.h b/include/linux/mm.h
> index 2f2199a51941..3d0efd937d2b 100644
> --- a/include/linux/mm.h
> +++ b/include/linux/mm.h
> @@ -695,11 +695,6 @@ static inline void *kvcalloc(size_t n, size_t size, gfp_t flags)
>   
>   extern void kvfree(const void *addr);
>   
> -static inline atomic_t *compound_mapcount_ptr(struct page *page)
> -{
> -	return &page[1].compound_mapcount;
> -}
> -
>   static inline int compound_mapcount(struct page *page)
>   {
>   	VM_BUG_ON_PAGE(!PageCompound(page), page);
> diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
> index 2222fa795284..270aa8fd2800 100644
> --- a/include/linux/mm_types.h
> +++ b/include/linux/mm_types.h
> @@ -221,6 +221,11 @@ struct page {
>   #endif
>   } _struct_page_alignment;
>   
> +static inline atomic_t *compound_mapcount_ptr(struct page *page)
> +{
> +	return &page[1].compound_mapcount;
> +}
> +
>   /*
>    * Used for sizing the vmemmap region on some architectures
>    */