Re: [PATCH] memcg: change behavior of moving charges at task move

Andrew Morton
2012-03-22T21:36:15Z

On Wed, 21 Mar 2012 18:52:04 +0900
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:

> static struct page *mc_handle_swap_pte(struct vm_area_struct *vma,
> unsigned long addr, pte_t ptent, swp_entry_t *entry)
> {
> - int usage_count;
> struct page *page = NULL;
> swp_entry_t ent = pte_to_swp_entry(ptent);
>
> if (!move_anon() || non_swap_entry(ent))
> return NULL;
> - usage_count = mem_cgroup_count_swap_user(ent, &page);
> - if (usage_count > 1) { /* we don't move shared anon */
> - if (page)
> - put_page(page);
> - return NULL;
> - }
> +#ifdef CONFIG_SWAP
> + /*
> + * Avoid lookup_swap_cache() not to update statistics.
> + */

I don't understand this comment - what is it trying to tell us?

> + page = find_get_page(&swapper_space, ent.val);

The code won't even compile if CONFIG_SWAP=n?

> +#endif
> if (do_swap_account)
> entry->val = ent.val;
>