Re: [PATCH] compaction: Remove mem_cgroup_del_lru

[Andrew Morton]

On Wed,  8 Dec 2010 00:01:26 +0900
Minchan Kim <minchan.kim@xxxxxxxxx> wrote:

> del_page_from_lru_list alreay called mem_cgroup_del_lru.
> So we need to call it again. It makes wrong stat of memcg and
> even happen VM_BUG_ON hit.
> 
> Cc: Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx>
> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
> Cc: Mel Gorman <mel@xxxxxxxxx>
> Signed-off-by: Minchan Kim <minchan.kim@xxxxxxxxx>
> ---
>  mm/compaction.c |    1 -
>  1 files changed, 0 insertions(+), 1 deletions(-)
> 
> diff --git a/mm/compaction.c b/mm/compaction.c
> index 50b0a90..b0fbfdf 100644
> --- a/mm/compaction.c
> +++ b/mm/compaction.c
> @@ -302,7 +302,6 @@ static unsigned long isolate_migratepages(struct zone *zone,
>  		/* Successfully isolated */
>  		del_page_from_lru_list(zone, page, page_lru(page));
>  		list_add(&page->lru, migratelist);
> -		mem_cgroup_del_lru(page);
>  		cc->nr_migratepages++;
>  		nr_isolated++;
>  

err, yes, that looks bad.

This bug is present in 2.6.35 and 2.6.36 afaict, so I tagged the fix
for -stable backporting.

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