Re: [Xen-devel] [PATCH v8, part3 12/14] mm: correctly update zone->mamaged_pages

[Liu Jiang <liuj97@xxxxxxxxx>]

Hi Sergei,
        Thanks for review!

On 05/27/2013 09:57 PM, Sergei Shtylyov wrote:
> On 26-05-2013 17:38, Jiang Liu wrote:
> 
>    Typo in the subject: s/mamaged_pages/managed_pages/.
Will fix it in next version.

> 
>> 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@xxxxxxxxxx>
>> Cc: Chris Metcalf <cmetcalf@xxxxxxxxxx>
>> Cc: Rusty Russell <rusty@xxxxxxxxxxxxxxx>
>> Cc: "Michael S. Tsirkin" <mst@xxxxxxxxxx>
>> Cc: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx>
>> Cc: Jeremy Fitzhardinge <jeremy@xxxxxxxx>
>> Cc: Wen Congyang <wency@xxxxxxxxxxxxxx>
>> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
>> Cc: Tang Chen <tangchen@xxxxxxxxxxxxxx>
>> Cc: Yasuaki Ishimatsu <isimatu.yasuaki@xxxxxxxxxxxxxx>
>> Cc: Mel Gorman <mgorman@xxxxxxx>
>> Cc: Minchan Kim <minchan@xxxxxxxxxx>
>> Cc: linux-kernel@xxxxxxxxxxxxxxx
>> Cc: virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx
>> Cc: xen-devel@xxxxxxxxxxxxxxxxxxx
>> Cc: linux-mm@xxxxxxxxx
>> ---
>>   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...
Good suggestion, will change it in next version.

> 
>>
>>       /* 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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