[-mm PATCH 6/9] Memory controller add per container LRU and reclaim (v4)

[YAMAMOTO Takashi]

> +unsigned long mem_container_isolate_pages(unsigned long nr_to_scan,
> +					struct list_head *dst,
> +					unsigned long *scanned, int order,
> +					int mode, struct zone *z,
> +					struct mem_container *mem_cont,
> +					int active)
> +{
> +	unsigned long nr_taken = 0;
> +	struct page *page;
> +	unsigned long scan;
> +	LIST_HEAD(mp_list);
> +	struct list_head *src;
> +	struct meta_page *mp;
> +
> +	if (active)
> +		src = &mem_cont->active_list;
> +	else
> +		src = &mem_cont->inactive_list;
> +
> +	for (scan = 0; scan < nr_to_scan && !list_empty(src); scan++) {
> +		mp = list_entry(src->prev, struct meta_page, lru);

what prevents another thread from freeing mp here?

> +		spin_lock(&mem_cont->lru_lock);
> +		if (mp)
> +			page = mp->page;
> +		spin_unlock(&mem_cont->lru_lock);
> +		if (!mp)
> +			continue;

YAMAMOTO Takashi