linux-kernel - Re: [PATCH v8, part3 12/14] mm: correctly update zone->mamaged

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Date:	Mon, 27 May 2013 17:57:07 +0400
From:	Sergei Shtylyov <sergei.shtylyov@...entembedded.com>
To:	Jiang Liu <liuj97@...il.com>
CC:	Andrew Morton <akpm@...ux-foundation.org>,
	Jiang Liu <jiang.liu@...wei.com>,
	David Rientjes <rientjes@...gle.com>,
	Wen Congyang <wency@...fujitsu.com>,
	Mel Gorman <mgorman@...e.de>, Minchan Kim <minchan@...nel.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Michal Hocko <mhocko@...e.cz>,
	James Bottomley <James.Bottomley@...senPartnership.com>,
	David Howells <dhowells@...hat.com>,
	Mark Salter <msalter@...hat.com>,
	Jianguo Wu <wujianguo@...wei.com>, linux-mm@...ck.org,
	linux-arch@...r.kernel.org, linux-kernel@...r.kernel.org,
	Chris Metcalf <cmetcalf@...era.com>,
	Rusty Russell <rusty@...tcorp.com.au>,
	"Michael S. Tsirkin" <mst@...hat.com>,
	Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>,
	Jeremy Fitzhardinge <jeremy@...p.org>,
	Tang Chen <tangchen@...fujitsu.com>,
	Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>,
	virtualization@...ts.linux-foundation.org,
	xen-devel@...ts.xensource.com
Subject: Re: [PATCH v8, part3 12/14] mm: correctly update zone->mamaged_pages

On 26-05-2013 17:38, Jiang Liu wrote:

    Typo in the subject: s/mamaged_pages/managed_pages/.

> Enhance adjust_managed_page_count() to adjust totalhigh_pages for
> highmem pages. And change code which directly adjusts totalram_pages
> to use adjust_managed_page_count() because it adjusts totalram_pages,
> totalhigh_pages and zone->managed_pages altogether in a safe way.

> Remove inc_totalhigh_pages() and dec_totalhigh_pages() from xen/balloon
> driver bacause adjust_managed_page_count() has already adjusted
> totalhigh_pages.

> This patch also fixes two bugs:
> 1) enhances virtio_balloon driver to adjust totalhigh_pages when
>     reserve/unreserve pages.
> 2) enhance memory_hotplug.c to adjust totalhigh_pages when hot-removing
>     memory.

> We still need to deal with modifications of totalram_pages in file
> arch/powerpc/platforms/pseries/cmm.c, but need help from PPC experts.

> Signed-off-by: Jiang Liu <jiang.liu@...wei.com>
> Cc: Chris Metcalf <cmetcalf@...era.com>
> Cc: Rusty Russell <rusty@...tcorp.com.au>
> Cc: "Michael S. Tsirkin" <mst@...hat.com>
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@...cle.com>
> Cc: Jeremy Fitzhardinge <jeremy@...p.org>
> Cc: Wen Congyang <wency@...fujitsu.com>
> Cc: Andrew Morton <akpm@...ux-foundation.org>
> Cc: Tang Chen <tangchen@...fujitsu.com>
> Cc: Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>
> Cc: Mel Gorman <mgorman@...e.de>
> Cc: Minchan Kim <minchan@...nel.org>
> Cc: linux-kernel@...r.kernel.org
> Cc: virtualization@...ts.linux-foundation.org
> Cc: xen-devel@...ts.xensource.com
> Cc: linux-mm@...ck.org
> ---
>   drivers/virtio/virtio_balloon.c |  8 +++++---
>   drivers/xen/balloon.c           | 23 +++++------------------
>   mm/hugetlb.c                    |  2 +-
>   mm/memory_hotplug.c             | 16 +++-------------
>   mm/page_alloc.c                 | 10 +++++-----
>   5 files changed, 19 insertions(+), 40 deletions(-)

> diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c
> index bd3ae32..6649968 100644
> --- a/drivers/virtio/virtio_balloon.c
> +++ b/drivers/virtio/virtio_balloon.c
[...]
> @@ -160,11 +160,13 @@ static void fill_balloon(struct virtio_balloon *vb, size_t num)
>   static void release_pages_by_pfn(const u32 pfns[], unsigned int num)
>   {
>   	unsigned int i;
> +	struct page *page;

    Why not declare it right in the *for* loop? You could use intializer 
then...

>
>   	/* Find pfns pointing at start of each page, get pages and free them. */
>   	for (i = 0; i < num; i += VIRTIO_BALLOON_PAGES_PER_PAGE) {
> -		balloon_page_free(balloon_pfn_to_page(pfns[i]));
> -		totalram_pages++;
> +		page = balloon_pfn_to_page(pfns[i]);
> +		balloon_page_free(page);
> +		adjust_managed_page_count(page, 1);
>   	}
>   }
>
[...]

WBR, Sergei

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