Re: [RFC/PATCH 2/6] memcg: remove refcnt

[Li Zefan <lizf@cn.fujitsu.com>]

>  /*
> - * Uncharging is always a welcome operation, we never complain, simply
> - * uncharge.
> + * uncharge if !page_mapped(page)
>   */
> -void mem_cgroup_uncharge_page(struct page *page)
> +void __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype)

static void ?

>  {
>  	struct page_cgroup *pc;
>  	struct mem_cgroup *mem;
> @@ -704,29 +693,41 @@ void mem_cgroup_uncharge_page(struct pag
>  		goto unlock;
>  

[..snip..]

> Index: linux-2.6.26-rc2/include/linux/memcontrol.h
> ===================================================================
> --- linux-2.6.26-rc2.orig/include/linux/memcontrol.h
> +++ linux-2.6.26-rc2/include/linux/memcontrol.h
> @@ -35,6 +35,8 @@ extern int mem_cgroup_charge(struct page
>  extern int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
>  					gfp_t gfp_mask);
>  extern void mem_cgroup_uncharge_page(struct page *page);
> +extern void mem_cgroup_uncharge_cache_page(struct page *page);
> +extern int mem_cgroup_shrink_usage(struct mm_struct *mm, gfp_t gfp_mask);

This function is defined and used in the 4th patch, so the declaration
should be moved to that patch.

>  extern void mem_cgroup_move_lists(struct page *page, bool active);
>  extern unsigned long mem_cgroup_isolate_pages(unsigned long nr_to_scan,
>  					struct list_head *dst,
> @@ -53,7 +55,6 @@ extern struct mem_cgroup *mem_cgroup_fro
>  extern int
>  mem_cgroup_prepare_migration(struct page *page, struct page *newpage);
>  extern void mem_cgroup_end_migration(struct page *page);
> -extern int mem_cgroup_getref(struct page *page);
>  
>  /*
>   * For memory reclaim.
> @@ -97,6 +98,14 @@ static inline int mem_cgroup_cache_charg
>  static inline void mem_cgroup_uncharge_page(struct page *page)
>  {
>  }

need a blank line here

> +static inline void mem_cgroup_uncharge_cache_page(struct page *page)
> +{
> +}
> +

[..snip..]

>  #ifdef CONFIG_DEBUG_VM
> Index: linux-2.6.26-rc2/mm/shmem.c
> ===================================================================
> --- linux-2.6.26-rc2.orig/mm/shmem.c
> +++ linux-2.6.26-rc2/mm/shmem.c
> @@ -961,13 +961,14 @@ found:
>  		shmem_swp_unmap(ptr);
>  	spin_unlock(&info->lock);
>  	radix_tree_preload_end();
> -uncharge:
> -	mem_cgroup_uncharge_page(page);
>  out:
>  	unlock_page(page);
>  	page_cache_release(page);
>  	iput(inode);		/* allows for NULL */
>  	return error;
> +uncharge:
> +	mem_cgroup_uncharge_cache_page(page);
> +	goto out;
>  }
>  

Seems the logic is changed here. is it intended ?