On Sun, Feb 20, 2011 at 11:43:37PM +0900, Minchan Kim wrote:
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -813,6 +813,33 @@ void mem_cgroup_del_lru(struct page *page)
> mem_cgroup_del_lru_list(page, page_lru(page));
> }
>
> +/*
> + * Writeback is about to end against a page which has been marked for immediate
> + * reclaim. If it still appears to be reclaimable, move it to the tail of the
> + * inactive list.
> + */
> +void mem_cgroup_rotate_reclaimable_page(struct page *page)
> +{
> + struct mem_cgroup_per_zone *mz;
> + struct page_cgroup *pc;
> + enum lru_list lru = page_lru(page);
> +
> + if (mem_cgroup_disabled())
> + return;
> +
> + pc = lookup_page_cgroup(page);
> + /*
> + * Used bit is set without atomic ops but after smp_wmb().
> + * For making pc->mem_cgroup visible, insert smp_rmb() here.
> + */
> + smp_rmb();
> + /* unused or root page is not rotated. */
> + if (!PageCgroupUsed(pc) || mem_cgroup_is_root(pc->mem_cgroup))
> + return;
The placement of this barrier is confused and has been fixed up in the
meantime in other places. It has to be between PageCgroupUsed() and
accessing pc->mem_cgroup. You can look at the other memcg lru
functions for reference.
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