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Reply-To: "Hillf Danton" <hillf.zj@alibaba-inc.com>
From: "Hillf Danton" <hillf.zj@alibaba-inc.com>
To: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Cc: "linux-kernel" <linux-kernel@vger.kernel.org>, <linux-mm@kvack.org>,
        "Hillf Danton" <hillf.zj@alibaba-inc.com>
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In-Reply-To: <010501d062df$05125160$0f36f420$@alibaba-inc.com>
Subject: Re: [PATCH 04/16] page-flags: define PG_locked behavior on compound pages
Date: Fri, 20 Mar 2015 15:32:05 +0800
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> --- a/include/linux/page-flags.h
> +++ b/include/linux/page-flags.h
> @@ -269,7 +269,7 @@ static inline struct page *compound_head_fast(struct page *page)
>  	return page;
>  }
> 
> -TESTPAGEFLAG(Locked, locked, ANY)
> +__PAGEFLAG(Locked, locked, NO_TAIL)
>  PAGEFLAG(Error, error, ANY) TESTCLEARFLAG(Error, error, ANY)
>  PAGEFLAG(Referenced, referenced, ANY) TESTCLEARFLAG(Referenced, referenced, ANY)
>  	__SETPAGEFLAG(Referenced, referenced, ANY)
[...]
> @@ -490,9 +481,9 @@ extern int wait_on_page_bit_killable_timeout(struct page *page,
> 
>  static inline int wait_on_page_locked_killable(struct page *page)
>  {
> -	if (PageLocked(page))
> -		return wait_on_page_bit_killable(page, PG_locked);
> -	return 0;
> +	if (!PageLocked(page))
> +		return 0;

I am lost here: can we feed any page to NO_TAIL operation?

> +	return wait_on_page_bit_killable(compound_head(page), PG_locked);
>  }
>