Re: [PATCH] memcg: fix mem_cgroup_isolate_lru_page to use the same rotate logic at busy path

Daisuke Nishimura
2009-06-10T00:12:09Z

On Tue, 9 Jun 2009 18:22:53 +0900, KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
>
> This patch tries to fix memcg's lru rotation sanity...make memcg use
> the same logic as global LRU does.
>
> Now, at __isolate_lru_page() retruns -EBUSY, the page is rotated to
> the tail of LRU in global LRU's isolate LRU pages. But in memcg,
> it's not handled. This makes memcg do the same behavior as global LRU
> and rotate LRU in the page is busy.
>
> Note: __isolate_lru_page() is not isolate_lru_page() and it's just used
> in sc->isolate_pages() logic.
>
> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
>
Looks good to me.

Reviewed-by: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>

> ---
> mm/memcontrol.c | 13 ++++++++++++-
> mm/vmscan.c | 4 +++-
> 2 files changed, 15 insertions(+), 2 deletions(-)
>
> Index: mmotm-2.6.30-Jun4/mm/vmscan.c
> ===================================================================
> --- mmotm-2.6.30-Jun4.orig/mm/vmscan.c
> +++ mmotm-2.6.30-Jun4/mm/vmscan.c
> @@ -842,7 +842,6 @@ int __isolate_lru_page(struct page *page
> */
> ClearPageLRU(page);
> ret = 0;
> - mem_cgroup_del_lru(page);
> }
>
> return ret;
> @@ -890,12 +889,14 @@ static unsigned long isolate_lru_pages(u
> switch (__isolate_lru_page(page, mode, file)) {
> case 0:
> list_move(&page->lru, dst);
> + mem_cgroup_del_lru(page);
> nr_taken++;
> break;
>
> case -EBUSY:
> /* else it is being freed elsewhere */
> list_move(&page->lru, src);
> + mem_cgroup_rotate_lru_list(page, page_lru(page));
> continue;
>
> default:
> @@ -937,6 +938,7 @@ static unsigned long isolate_lru_pages(u
> switch (__isolate_lru_page(cursor_page, mode, file)) {
> case 0:
> list_move(&cursor_page->lru, dst);
> + mem_cgroup_del_lru(page);
> nr_taken++;
> scan++;
> break;
> Index: mmotm-2.6.30-Jun4/mm/memcontrol.c
> ===================================================================
> --- mmotm-2.6.30-Jun4.orig/mm/memcontrol.c
> +++ mmotm-2.6.30-Jun4/mm/memcontrol.c
> @@ -649,6 +649,7 @@ unsigned long mem_cgroup_isolate_pages(u
> int zid = zone_idx(z);
> struct mem_cgroup_per_zone *mz;
> int lru = LRU_FILE * !!file + !!active;
> + int ret;
>
> BUG_ON(!mem_cont);
> mz = mem_cgroup_zoneinfo(mem_cont, nid, zid);
> @@ -666,9 +667,19 @@ unsigned long mem_cgroup_isolate_pages(u
> continue;
>
> scan++;
> - if (__isolate_lru_page(page, mode, file) == 0) {
> + ret = __isolate_lru_page(page, mode, file);
> + switch (ret) {
> + case 0:
> list_move(&page->lru, dst);
> + mem_cgroup_del_lru(page);
> nr_taken++;
> + break;
> + case -EBUSY:
> + /* we don't affect global LRU but rotate in our LRU */
> + mem_cgroup_rotate_lru_list(page, page_lru(page));
> + break;
> + default:
> + break;
> }
> }