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Message-ID: <20151105080910.GA25938@js1304-P5Q-DELUXE>
Date: Thu, 5 Nov 2015 17:09:10 +0900
From: Joonsoo Kim <iamjoonsoo.kim@....com>
To: Vlastimil Babka <vbabka@...e.cz>
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org,
Minchan Kim <minchan@...nel.org>,
Sasha Levin <sasha.levin@...cle.com>,
"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
Mel Gorman <mgorman@...e.de>
Subject: Re: [PATCH 1/5] mm, page_owner: print migratetype of a page, not
pageblock
On Wed, Nov 04, 2015 at 04:00:57PM +0100, Vlastimil Babka wrote:
> The information in /sys/kernel/debug/page_owner includes the migratetype
> declared during the page allocation via gfp_flags. This is also checked against
> the pageblock's migratetype, and reported as Fallback allocation if these two
> differ (although in fact fallback allocation is not the only reason why they
> can differ).
>
> However, the migratetype actually printed is the one of the pageblock, not of
> the page itself, so it's the same for all pages in the pageblock. This is
> apparently a bug, noticed when working on other page_owner improvements. Fixed.
We can guess page migratetype through gfp_mask output although it isn't
easy task for now. But, there is no way to know pageblock migratetype.
I used this to know how memory is fragmented.
Thanks.
>
> Signed-off-by: Vlastimil Babka <vbabka@...e.cz>
> ---
> mm/page_owner.c | 2 +-
> 1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/mm/page_owner.c b/mm/page_owner.c
> index 983c3a1..a9f16b8 100644
> --- a/mm/page_owner.c
> +++ b/mm/page_owner.c
> @@ -113,7 +113,7 @@ print_page_owner(char __user *buf, size_t count, unsigned long pfn,
> "PFN %lu Block %lu type %d %s Flags %s%s%s%s%s%s%s%s%s%s%s%s\n",
> pfn,
> pfn >> pageblock_order,
> - pageblock_mt,
> + page_mt,
> pageblock_mt != page_mt ? "Fallback" : " ",
> PageLocked(page) ? "K" : " ",
> PageError(page) ? "E" : " ",
> --
> 2.6.2
>
> --
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