Re: [patch 13/13] mm: memcontrol: rewrite uncharge API

From: Naoya Horiguchi
Date: Tue Jul 15 2014 - 11:56:26 EST

On Wed, Jun 18, 2014 at 04:40:45PM -0400, Johannes Weiner wrote:
> diff --git a/mm/swap.c b/mm/swap.c
> index a98f48626359..3074210f245d 100644
> --- a/mm/swap.c
> +++ b/mm/swap.c
> @@ -62,6 +62,7 @@ static void __page_cache_release(struct page *page)
> del_page_from_lru_list(page, lruvec, page_off_lru(page));
> spin_unlock_irqrestore(&zone->lru_lock, flags);
> }
> + mem_cgroup_uncharge(page);
> }
> static void __put_single_page(struct page *page)

This seems to cause a list breakage in hstate->hugepage_activelist
when freeing a hugetlbfs page.
For hugetlbfs, we uncharge in free_huge_page() which is called after
__page_cache_release(), so I think that we don't have to uncharge here.

In my testing, moving mem_cgroup_uncharge() inside if (PageLRU) block
fixed the problem, so if that works for you, could you fold the change
into your patch?

Naoya Horiguchi
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