Re: [PATCH] vmscan,memcg: memcg aware swap token

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

On Mon, 25 Apr 2011 11:21:57 +0900 (JST)
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> wrote:

> The better approach is swap-token recognize memcg and behave clever? :)
> 
> 
> 
> From 106c21d7f9cf8641592cbfe1416af66470af4f9a Mon Sep 17 00:00:00 2001
> From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
> Date: Mon, 25 Apr 2011 10:57:54 +0900
> Subject: [PATCH] vmscan,memcg: memcg aware swap token
> 
> Currently, memcg reclaim can disable swap token even if the swap token
> mm doesn't belong in its memory cgroup. It's slightly riskly. If an
> admin makes very small mem-cgroup and silly guy runs contenious heavy
> memory pressure workloa, whole tasks in the system are going to lose
> swap-token and then system may become unresponsive. That's bad.
> 
> This patch adds 'memcg' parameter into disable_swap_token(). and if
> the parameter doesn't match swap-token, VM doesn't put swap-token.
> 
> Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>

Oh, thank you.  This seems necessary. But..we should maintain swap token
under memcg with considering hierarchy, I think. 

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

(It's ok to update this by myself if hierarchy seems complicated.)


> ---
>  include/linux/memcontrol.h |    6 ++++++
>  include/linux/swap.h       |   24 +++++++++++++++++-------
>  mm/memcontrol.c            |    2 +-
>  mm/thrash.c                |   17 +++++++++++++++++
>  mm/vmscan.c                |    4 ++--
>  5 files changed, 43 insertions(+), 10 deletions(-)
> 
> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
> index 6a0cffd..df572af 100644
> --- a/include/linux/memcontrol.h
> +++ b/include/linux/memcontrol.h
> @@ -84,6 +84,7 @@ int task_in_mem_cgroup(struct task_struct *task, const struct mem_cgroup *mem);
>  
>  extern struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page);
>  extern struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p);
> +extern struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm);
>  
>  static inline
>  int mm_match_cgroup(const struct mm_struct *mm, const struct mem_cgroup *cgroup)
> @@ -244,6 +245,11 @@ static inline struct mem_cgroup *try_get_mem_cgroup_from_page(struct page *page)
>  	return NULL;
>  }
>  
> +static inline struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm)
> +{
> +	return NULL;
> +}
> +
>  static inline int mm_match_cgroup(struct mm_struct *mm, struct mem_cgroup *mem)
>  {
>  	return 1;
> diff --git a/include/linux/swap.h b/include/linux/swap.h
> index 384eb5f..ccea15d 100644
> --- a/include/linux/swap.h
> +++ b/include/linux/swap.h
> @@ -358,21 +358,31 @@ struct backing_dev_info;
>  extern struct mm_struct *swap_token_mm;
>  extern void grab_swap_token(struct mm_struct *);
>  extern void __put_swap_token(struct mm_struct *);
> +extern int has_swap_token_memcg(struct mm_struct *mm, struct mem_cgroup *memcg);
>  
> -static inline int has_swap_token(struct mm_struct *mm)
> +static inline
> +int has_swap_token(struct mm_struct *mm)
>  {
> -	return (mm == swap_token_mm);
> +	return has_swap_token_memcg(mm, NULL);
>  }
>  
> -static inline void put_swap_token(struct mm_struct *mm)
> +static inline
> +void put_swap_token_memcg(struct mm_struct *mm, struct mem_cgroup *memcg)
>  {
> -	if (has_swap_token(mm))
> +	if (has_swap_token_memcg(mm, memcg))
>  		__put_swap_token(mm);
>  }
>  
> -static inline void disable_swap_token(void)
> +static inline
> +void put_swap_token(struct mm_struct *mm)
> +{
> +	return put_swap_token_memcg(mm, NULL);
> +}
> +
> +static inline
> +void disable_swap_token(struct mem_cgroup *memcg)
>  {
> -	put_swap_token(swap_token_mm);
> +	put_swap_token_memcg(swap_token_mm, memcg);
>  }
>  
>  #ifdef CONFIG_CGROUP_MEM_RES_CTLR
> @@ -500,7 +510,7 @@ static inline int has_swap_token(struct mm_struct *mm)
>  	return 0;
>  }
>  
> -static inline void disable_swap_token(void)
> +static inline void disable_swap_token(struct mem_cgroup *memcg)
>  {
>  }
>  
> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index c2776f1..5683c7a 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -735,7 +735,7 @@ struct mem_cgroup *mem_cgroup_from_task(struct task_struct *p)
>  				struct mem_cgroup, css);
>  }
>  
> -static struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm)
> +struct mem_cgroup *try_get_mem_cgroup_from_mm(struct mm_struct *mm)
>  {
>  	struct mem_cgroup *mem = NULL;
>  
> diff --git a/mm/thrash.c b/mm/thrash.c
> index 2372d4e..f892a6e 100644
> --- a/mm/thrash.c
> +++ b/mm/thrash.c
> @@ -21,6 +21,7 @@
>  #include <linux/mm.h>
>  #include <linux/sched.h>
>  #include <linux/swap.h>
> +#include <linux/memcontrol.h>
>  
>  static DEFINE_SPINLOCK(swap_token_lock);
>  struct mm_struct *swap_token_mm;
> @@ -75,3 +76,19 @@ void __put_swap_token(struct mm_struct *mm)
>  		swap_token_mm = NULL;
>  	spin_unlock(&swap_token_lock);
>  }
> +
> +int has_swap_token_memcg(struct mm_struct *mm, struct mem_cgroup *memcg)
> +{
> +	if (memcg) {
> +		struct mem_cgroup *swap_token_memcg;
> +
> +		/*
> +		 * memcgroup reclaim can disable swap token only if token task
> +		 * is in the same cgroup.
> +		 */
> +		swap_token_memcg = try_get_mem_cgroup_from_mm(swap_token_mm);
> +		return ((mm == swap_token_mm) && (memcg == swap_token_memcg));
> +	} else
> +		return (mm == swap_token_mm);
> +}
> +
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index b3a569f..19e179b 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -2044,7 +2044,7 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist,
>  	for (priority = DEF_PRIORITY; priority >= 0; priority--) {
>  		sc->nr_scanned = 0;
>  		if (!priority)
> -			disable_swap_token();
> +			disable_swap_token(sc->mem_cgroup);
>  		shrink_zones(priority, zonelist, sc);
>  		/*
>  		 * Don't shrink slabs when reclaiming memory from
> @@ -2353,7 +2353,7 @@ loop_again:
>  
>  		/* The swap token gets in the way of swapout... */
>  		if (!priority)
> -			disable_swap_token();
> +			disable_swap_token(NULL);
>  
>  		all_zones_ok = 1;
>  		balanced = 0;
> -- 
> 1.7.3.1
> 
> 
> 
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