Re: [PATCH v2 5/5] power: add zone range overlapping check

Vlastimil Babka
2016-04-01T08:19:30Z

On 1.4.2016 4:06, js1304@gmail.com wrote:
> From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
>
> There is a system that node's pfn are overlapped like as following.
>
> -----pfn-------->
> N0 N1 N2 N0 N1 N2
>
> Therefore, we need to care this overlapping when iterating pfn range.
>
> mark_free_pages() iterates requested zone's pfn range and unset
> all range's bitmap first. And then it marks freepages in a zone
> to the bitmap. If there is an overlapping zone, above unset could
> clear previous marked bit and reference to this bitmap in the future
> will cause the problem. To prevent it, this patch adds a zone check
> in mark_free_pages().
>
> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>

Acked-by: Vlastimil Babka <vbabka@suse.cz>

> ---
> mm/page_alloc.c | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index 0cfee62..437a934 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -2156,6 +2156,10 @@ void mark_free_pages(struct zone *zone)
> for (pfn = zone->zone_start_pfn; pfn < max_zone_pfn; pfn++)
> if (pfn_valid(pfn)) {
> page = pfn_to_page(pfn);
> +
> + if (page_zone(page) != zone)
> + continue;
> +
> if (!swsusp_page_is_forbidden(page))
> swsusp_unset_page_free(page);
> }
>