Re: [PATCH 1/2] memcg: fix page_referencies cgroup filter on global reclaim

[KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

On Wed, 15 Feb 2012 20:28:30 +0400
Konstantin Khlebnikov <khlebnikov@openvz.org> wrote:

> Global memory reclaimer should't skip referencies for any pages,
> even if they are shared between different cgroups.
> 
> This patch adds scan_control->current_mem_cgroup, which points to currently
> shrinking sub-cgroup in hierarchy, at global reclaim it always NULL.
> 
> Signed-off-by: Konstantin Khlebnikov <khlebnikov@openvz.org>

seems ok to me. How about you, Johannes ?

Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>


> ---
>  mm/vmscan.c |   18 ++++++++++++++----
>  1 files changed, 14 insertions(+), 4 deletions(-)
> 
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 531abcc..b069fac 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -109,6 +109,12 @@ struct scan_control {
>  	struct mem_cgroup *target_mem_cgroup;
>  
>  	/*
> +	 * Currently reclaiming memory cgroup in hierarchy,
> +	 * NULL for global reclaim.
> +	 */
> +	struct mem_cgroup *current_mem_cgroup;
> +
> +	/*
>  	 * Nodemask of nodes allowed by the caller. If NULL, all nodes
>  	 * are scanned.
>  	 */
> @@ -703,13 +709,13 @@ enum page_references {
>  };
>  
>  static enum page_references page_check_references(struct page *page,
> -						  struct mem_cgroup_zone *mz,
>  						  struct scan_control *sc)
>  {
>  	int referenced_ptes, referenced_page;
>  	unsigned long vm_flags;
>  
> -	referenced_ptes = page_referenced(page, 1, mz->mem_cgroup, &vm_flags);
> +	referenced_ptes = page_referenced(page, 1,
> +			sc->current_mem_cgroup, &vm_flags);
>  	referenced_page = TestClearPageReferenced(page);
>  
>  	/* Lumpy reclaim - ignore references */
> @@ -830,7 +836,7 @@ static unsigned long shrink_page_list(struct list_head *page_list,
>  			}
>  		}
>  
> -		references = page_check_references(page, mz, sc);
> +		references = page_check_references(page, sc);
>  		switch (references) {
>  		case PAGEREF_ACTIVATE:
>  			goto activate_locked;
> @@ -1744,7 +1750,7 @@ static void shrink_active_list(unsigned long nr_to_scan,
>  			continue;
>  		}
>  
> -		if (page_referenced(page, 0, mz->mem_cgroup, &vm_flags)) {
> +		if (page_referenced(page, 0, sc->current_mem_cgroup, &vm_flags)) {
>  			nr_rotated += hpage_nr_pages(page);
>  			/*
>  			 * Identify referenced, file-backed active pages and
> @@ -2163,6 +2169,9 @@ static void shrink_zone(int priority, struct zone *zone,
>  			.zone = zone,
>  		};
>  
> +		if (!global_reclaim(sc))
> +			sc->current_mem_cgroup = memcg;
> +
>  		shrink_mem_cgroup_zone(priority, &mz, sc);
>  		/*
>  		 * Limit reclaim has historically picked one memcg and
> @@ -2478,6 +2487,7 @@ unsigned long mem_cgroup_shrink_node_zone(struct mem_cgroup *memcg,
>  		.may_swap = !noswap,
>  		.order = 0,
>  		.target_mem_cgroup = memcg,
> +		.current_mem_cgroup = memcg,
>  	};
>  	struct mem_cgroup_zone mz = {
>  		.mem_cgroup = memcg,
> 
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