Re: [PATCH 3/7] memcg: move_lists

[Balbir Singh <balbir@linux.vnet.ibm.com>]

* KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> [2008-03-14 19:07:31]:

> Modifies mem_cgroup_move_lists() to use get_page_cgroup().
> No major algorithm changes just adjusted to new locks.
> 
> Signed-off-By: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> 
>  mm/memcontrol.c |   16 +++++++++-------
>  1 file changed, 9 insertions(+), 7 deletions(-)
> 
> Index: mm-2.6.25-rc5-mm1/mm/memcontrol.c
> ===================================================================
> --- mm-2.6.25-rc5-mm1.orig/mm/memcontrol.c
> +++ mm-2.6.25-rc5-mm1/mm/memcontrol.c
> @@ -309,6 +309,10 @@ void mem_cgroup_move_lists(struct page *
>  	struct mem_cgroup_per_zone *mz;
>  	unsigned long flags;
> 
> +	/* This GFP will be ignored..*/
> +	pc = get_page_cgroup(page, GFP_ATOMIC, false);
> +	if (!pc)
> +		return;

Splitting get_page_cgroup will help avoid thse kinds of hacks. Please
see my earlier comment.

>  	/*
>  	 * We cannot lock_page_cgroup while holding zone's lru_lock,
>  	 * because other holders of lock_page_cgroup can be interrupted
> @@ -316,17 +320,15 @@ void mem_cgroup_move_lists(struct page *
>  	 * safely get to page_cgroup without it, so just try_lock it:
>  	 * mem_cgroup_isolate_pages allows for page left on wrong list.
>  	 */
> -	if (!try_lock_page_cgroup(page))
> +	if (!spin_trylock_irqsave(&pc->lock, flags))
>  		return;
> -
> -	pc = page_get_page_cgroup(page);
> -	if (pc) {
> +	if (pc->refcnt) {
>  		mz = page_cgroup_zoneinfo(pc);
> -		spin_lock_irqsave(&mz->lru_lock, flags);
> +		spin_lock(&mz->lru_lock);
>  		__mem_cgroup_move_lists(pc, active);
> -		spin_unlock_irqrestore(&mz->lru_lock, flags);
> +		spin_unlock(&mz->lru_lock);
>  	}
> -	unlock_page_cgroup(page);
> +	spin_unlock_irqrestore(&pc->lock, flags);
>  }
> 
>  /*
> 

-- 
	Warm Regards,
	Balbir Singh
	Linux Technology Center
	IBM, ISTL

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