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

[Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>]

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;
>  		}
>  	}
>  
> 

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