[RFC V4] mm:add KPF_ZERO_PAGE flag for /proc/kpageflags

[kirill@shutemov.name (Kirill A. Shutemov)]

On Mon, Dec 08, 2014 at 10:00:50AM +0800, Wang, Yalin wrote:
> This patch add KPF_ZERO_PAGE flag for zero_page,
> so that userspace process can notice zero_page from
> /proc/kpageflags, and then do memory analysis more accurately.
> 
> Signed-off-by: Yalin Wang <yalin.wang@sonymobile.com>
> ---
>  Documentation/vm/pagemap.txt           |  5 +++++
>  fs/proc/page.c                         | 16 +++++++++++++---
>  include/linux/huge_mm.h                | 12 ++++++++++++
>  include/uapi/linux/kernel-page-flags.h |  1 +
>  mm/huge_memory.c                       |  7 +------
>  5 files changed, 32 insertions(+), 9 deletions(-)
> 
> diff --git a/Documentation/vm/pagemap.txt b/Documentation/vm/pagemap.txt
> index 5948e45..fdeb06e 100644
> --- a/Documentation/vm/pagemap.txt
> +++ b/Documentation/vm/pagemap.txt
> @@ -62,6 +62,8 @@ There are three components to pagemap:
>      20. NOPAGE
>      21. KSM
>      22. THP
> +    23. BALLOON
> +    24. ZERO_PAGE
>  
>  Short descriptions to the page flags:
>  
> @@ -102,6 +104,9 @@ Short descriptions to the page flags:
>  22. THP
>      contiguous pages which construct transparent hugepages
>  
> +24. ZERO_PAGE
> +    zero page for pfn_zero or huge_zero page
> +
>      [IO related page flags]
>   1. ERROR     IO error occurred
>   3. UPTODATE  page has up-to-date data

Would be nice to document BALLOON while you're there.
Otherwise looks good to me.

Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>

-- 
 Kirill A. Shutemov