Re: [PATCH v4 1/4] mm/page_alloc: fix incorrect isolation behavior by rechecking migratetype

[Vlastimil Babka]

On 10/23/2014 10:10 AM, Joonsoo Kim wrote:
> Changes from v3:
> Add one more check in free_one_page() that checks whether migratetype is
> MIGRATE_ISOLATE or not. Without this, abovementioned case 1 could happens.

Good catch.

> Cc: <stable@xxxxxxxxxxxxxxx>
> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>

Acked-by: Vlastimil Babka <vbabka@xxxxxxx>

(minor suggestion below)

> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -749,9 +749,16 @@ static void free_one_page(struct zone *zone,
>  	if (nr_scanned)
>  		__mod_zone_page_state(zone, NR_PAGES_SCANNED, -nr_scanned);
>  
> +	if (unlikely(has_isolate_pageblock(zone) ||

Would it make any difference if this was read just once and not in each
loop iteration?


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